docs: add Architecture section, update Process, add Weekplanner docs

- New Architecture section with ecosystem overview, systems table, shared JWT auth, repository map
- 4 seed ADRs (shared JWT, DB-first VTA, split repos foodplanner, docs split)
- New branch-strategy.md replacing GitFlow with trunk-based development
- Updated code_workflow.md to remove GitFlow references
- New Weekplanner development guide
- Added CONTRIBUTING.md and CODEOWNERS
- Redirected old architecture.md to new Architecture section
- Updated navigation and index
- Added search exclusion for Archive

Author: nbhansen

.github/CODEOWNERS

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+* @aau-giraf/maintainers

CONTRIBUTING.md

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+# Contributing to the GIRAF Wiki
+
+For general workflow and guidelines, see the [organization CONTRIBUTING.md](https://github.com/aau-giraf/.github/blob/main/CONTRIBUTING.md).
+
+## Development Setup
+
+### Prerequisites
+
+- Python 3.x
+- pip
+
+### Local Development
+
+```bash
+pip install mkdocs-material mkdocs-awesome-pages-plugin
+mkdocs serve                  # Dev server at localhost:8000
+```
+
+### Page Conventions
+
+- Each section has an `index.md` as its landing page
+- Use `.pages` files to control navigation order
+- Place images in `docs/resources/`
+
+### Creating Pages
+
+1. Add your `.md` file in the appropriate section under `docs/`
+2. Update the section's `.pages` file to include it
+3. Verify with `mkdocs build` — should produce zero warnings

docs/.pages

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     - ...
     - Onboarding
     - Process
+    - Architecture
     - Development
     - Legal
     - About

docs/Architecture/.pages

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+arrange:
+    - index.md
+    - decisions

docs/Architecture/decisions/.pages

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+arrange:
+    - TEMPLATE.md
+    - ...

docs/Architecture/decisions/0001-shared-jwt-auth.md

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+# 1. Shared JWT Auth
+
+**Date:** 2025-01-01
+
+**Status:** accepted
+
+## Context
+
+Multiple app backends need to authorize requests from users who authenticate with Core. Calling Core on every request adds latency and a single point of failure.
+
+## Decision
+
+Core issues JWTs with an `org_roles` claim. All backends validate locally using a shared `JWT_SECRET` (HS256). Role hierarchy: owner > admin > member.
+
+## Consequences
+
+Backends authorize without network calls. Adding a new backend only requires the shared secret. Revoking access requires token expiry (no instant revocation). Secret rotation requires coordinated deployment.

docs/Architecture/decisions/0002-db-first-vta.md

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+# 2. DB-First for VTA
+
+**Date:** 2025-01-01
+
+**Status:** accepted
+
+## Context
+
+VTA's database schema predates the current .NET backend. Schema changes are designed in MySQL directly by developers familiar with SQL.
+
+## Decision
+
+Use DB-first with `dotnet ef dbcontext scaffold` instead of code-first migrations. `mysql_schema.sql` is the schema source of truth.
+
+## Consequences
+
+Schema changes are explicit SQL. No migration conflicts. Developers must scaffold after schema changes. Can't use EF migration tooling for rollbacks.

docs/Architecture/decisions/0003-split-repos-foodplanner.md

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+# 3. Split Repos for Foodplanner
+
+**Date:** 2025-01-01
+
+**Status:** accepted
+
+## Context
+
+Foodplanner frontend (Flutter) and backend (.NET) have different CI pipelines, dependencies, and deployment targets.
+
+## Decision
+
+Separate repos (`foodplanner` for frontend, `foodplanner-api` for backend). VTA keeps its monorepo since frontend and backend are tightly coupled (SignalR real-time sync).
+
+## Consequences
+
+Independent CI/CD per component. Separate versioning. API contract changes require coordinated PRs across repos.

docs/Architecture/decisions/0004-docs-wiki-plus-website.md

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+# 4. Docs: Wiki + Website
+
+**Date:** 2025-01-01
+
+**Status:** accepted
+
+## Context
+
+GIRAF needs both contributor-facing technical docs and a public-facing project site. MkDocs suits structured technical docs; Jekyll suits blog-style public content.
+
+## Decision
+
+MkDocs wiki (`aau-giraf/wiki`) for contributor docs. Jekyll website (`GIRAF-website`) for public project information.
+
+## Consequences
+
+Two doc systems to maintain. Clear audience separation. Contributors use markdown in wiki repo. Public content managed separately.

docs/Architecture/decisions/TEMPLATE.md

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+# [NUMBER]. [TITLE]
+
+**Date:** YYYY-MM-DD
+
+**Status:** [proposed | accepted | deprecated | superseded by [ADR-NNNN](NNNN-*.md)]
+
+## Context
+
+[What is the issue that we're seeing that is motivating this decision or change?]
+
+## Decision
+
+[What is the change that we're proposing and/or doing?]
+
+## Consequences
+
+[What becomes easier or more difficult to do because of this change?]