docs: integrate Pagefind search, Google Analytics, and feedback buttons (#2670)

## Description

### Key Changes

- Added Google Analytics tracking ID.
- Added on-page feedback buttons for documentation.
- Adds estimated reading time for each page.
- Implemented Pagefind to replace the existing documentation search.

### Context: Pagefind Search Implementation

Unlike our previous in-memory search, Pagefind generates a highly
compressed, pre-calculated search index at build time. To support this:
- **CI/CD**: All deployment workflows (Cloudflare Pages, GitHub Pages,
and PR Previews) have been updated to automatically run ```npx pagefind
--site public``` immediately after the Hugo build step.
- **Local Development**: hugo server running solely in memory will no
longer render search results by default. Developers must generate the
physical files and index them locally using ```hugo --environment
development && npx pagefind ...``` before running the local server.
- **Docs & Config**: `DEVELOPER.md` and `gemini.md` have been updated
with the new local testing instructions, and `.hugo/static/pagefind/`
has been added to .gitignore to prevent committing local binary indexes.

### Rationale: Why Pagefind?

Why add a new build step and shift away from our default search?
Ultimately, we are trading a bit of build-time complexity for a leap in
user experience.

- Search Engine Experience: Instead of basic title matching or keyword
filtering, Pagefind provides relevant results, substring matching, and
highlights the exact context of the match directly in the search
dropdown.
- Better Scaling: It only delivers the exact data chunks needed for a
specific query, meaning our docs can grow and search will remain fast.
- Cleans Up Deployment Branches: Our previous search solution resulted
in numerous offline index files across our `versioned-gh-pages` branch,
contributing to repository bloat over time. Pagefind consolidates its
compressed chunks into a single pagefind/ directory, keeping our
deployment branches clean and tidy.


## PR Checklist

> Thank you for opening a Pull Request! Before submitting your PR, there
are a
> few things you can do to make sure it goes smoothly:

- [ ] Make sure you reviewed

[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [ ] Make sure to open an issue as a

[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
  before writing your code! That way we can discuss the change, evaluate
  designs, and agree on the general idea
- [ ] Ensure the tests and linter pass
- [ ] Code coverage does not decrease (if any source code was changed)
- [ ] Appropriate docs were updated (if necessary)
- [ ] Make sure to add `!` if this involve a breaking change

🛠️ Fixes #<issue_number_goes_here>

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: dishaprakash

.ci/lint-docs-source-page.sh

@@ -118,4 +118,4 @@ if has_errors:
     sys.exit(1)
 print("Success: Source pages validated.")
 sys.exit(0)
-EOF
+EOF

.ci/lint-docs-tool-page.sh

@@ -132,4 +132,4 @@ if has_errors:
     sys.exit(1)
 else:
     print("Success: All Tool pages passed structure validation.")
-EOF
+EOF

.github/workflows/deploy_dev_docs.yaml

@@ -69,6 +69,9 @@ jobs:
           HUGO_BASEURL: https://${{ github.repository_owner }}.github.io/${{ github.event.repository.name }}/dev
           HUGO_RELATIVEURLS: false
 
+      - name: Build Pagefind Search Index
+        run: npx pagefind --site public
+
       - name: Create Staging Directory
         run: |
           mkdir staging

.github/workflows/deploy_previous_version_docs.yaml

@@ -73,6 +73,10 @@ jobs:
           HUGO_RELATIVEURLS: false
           HUGO_PARAMS_VERSION: ${{ github.event.inputs.version_tag }}
 
+      - name: Build Pagefind Index (Archived Version)
+        run: npx pagefind --site public
+        working-directory: .hugo
+
       - name: Deploy to gh-pages
         uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4
         with:
@@ -95,6 +99,10 @@ jobs:
           HUGO_RELATIVEURLS: false
           HUGO_PARAMS_VERSION: ${{ github.event.inputs.version_tag }}
 
+      - name: Build Pagefind Index (Root)
+        run: npx pagefind --site public
+        working-directory: .hugo
+
       - name: Deploy to root
         uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4
         with:
@@ -103,4 +111,4 @@ jobs:
           publish_branch: versioned-gh-pages
           keep_files: true
           allow_empty_commit: true
-          commit_message: "deploy: docs to root for ${{ github.event.inputs.version_tag }}"
+          commit_message: "deploy: docs to root for ${{ github.event.inputs.version_tag }}"

.github/workflows/deploy_previous_version_docs_to_cf.yaml

@@ -73,6 +73,10 @@ jobs:
           HUGO_RELATIVEURLS: false
           HUGO_PARAMS_VERSION: ${{ github.event.inputs.version_tag }}
 
+      - name: Build Pagefind Index (Root)
+        run: npx pagefind --site public
+        working-directory: .hugo
+
       - name: Deploy to cloudflare-pages
         uses: peaceiris/actions-gh-pages@v4
         with:
@@ -95,6 +99,10 @@ jobs:
           HUGO_RELATIVEURLS: false
           HUGO_PARAMS_VERSION: ${{ github.event.inputs.version_tag }}
 
+      - name: Build Pagefind Index (Root)
+        run: npx pagefind --site public
+        working-directory: .hugo
+
       - name: Deploy to root
         uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4
         with:

.github/workflows/deploy_versioned_docs.yaml

@@ -63,6 +63,10 @@ jobs:
           HUGO_RELATIVEURLS: false
           HUGO_PARAMS_VERSION: ${{ steps.get_version.outputs.VERSION }}
 
+      - name: Build Pagefind Index (Versioned)
+        run: npx pagefind --site public
+        working-directory: .hugo
+
       - name: Deploy
         uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4
         with:
@@ -84,6 +88,10 @@ jobs:
           HUGO_RELATIVEURLS: false
           HUGO_PARAMS_VERSION: ${{ steps.get_version.outputs.VERSION }}
 
+      - name: Build Pagefind Index (Root)
+        run: npx pagefind --site public
+        working-directory: .hugo
+
       - name: Deploy to root
         uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4
         with:

.github/workflows/deploy_versioned_docs_to_cf.yaml

@@ -63,6 +63,10 @@ jobs:
           HUGO_RELATIVEURLS: false
           HUGO_PARAMS_VERSION: ${{ steps.get_version.outputs.VERSION }}
 
+      - name: Build Pagefind Index (Root)
+        run: npx pagefind --site public
+        working-directory: .hugo
+
       - name: Deploy
         uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4
         with:
@@ -84,6 +88,10 @@ jobs:
           HUGO_RELATIVEURLS: false
           HUGO_PARAMS_VERSION: ${{ steps.get_version.outputs.VERSION }}
 
+      - name: Build Pagefind Index (Root)
+        run: npx pagefind --site public
+        working-directory: .hugo
+
       - name: Deploy to root
         uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4
         with:

.github/workflows/docs_preview_deploy.yaml

@@ -17,7 +17,7 @@ name: "docs"
 permissions:
   contents: write
   pull-requests: write
-  
+
 # This Workflow depends on 'github.event.number',
 # not compatible with branch or manual triggers.
 on:
@@ -81,6 +81,9 @@ jobs:
           HUGO_ENVIRONMENT: preview
           HUGO_RELATIVEURLS: false
 
+      - name: Build Pagefind Search Index
+        run: npx pagefind --site public
+
       - name: Deploy
         uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4
         with:

.github/workflows/docs_preview_deploy_cf.yaml

@@ -72,6 +72,9 @@ jobs:
           HUGO_ENVIRONMENT: preview
           HUGO_RELATIVEURLS: false
 
+      - name: Build Pagefind Search Index
+        run: npx pagefind --site public
+
       - name: Deploy to Cloudflare Pages via Wrangler
         id: cf_deploy
         uses: cloudflare/wrangler-action@v3

.gitignore

@@ -13,6 +13,7 @@ node_modules
 # hugo
 .hugo/public/
 .hugo/resources/_gen
+.hugo/static/pagefind/
 .hugo_build.lock
 
 # coverage