chore: remove central node and associated code (#45)

Another cleanup to remove some unnecessary code. This used to be a
visual element for a center node in the middle of the chart that I
removed to make it visually cleaner. From here I think we can start
playing with things like font size and filtering to make the visual
easier to scan.

To test:
1. Make sure chart elements and interactions still function
2. Make sure title still says "Development Seed"

<img width="966" height="233" alt="Screenshot 2026-02-09 at 7 54 48 AM"
src="https://github.com/user-attachments/assets/496f7508-13cc-4e0a-bfad-b69d734e8fe5"
/>

<img width="966" height="874" alt="Screenshot 2026-02-09 at 7 54 29 AM"
src="https://github.com/user-attachments/assets/59931b00-7bc0-491a-9752-90b27acb002f"
/>

Author: aboydnw

assets/data/config.json

@@ -2,7 +2,7 @@
   "title": "The Development Seed Contributor Network",
   "author": "Pete Gadomski",
   "description": "An interactive visualization of contributors to Development Seed code and their connections to other repositories",
-  "central_repository": "developmentseed/DevSeed Team",
+  "organization_name": "Development Seed",
   "contributor_padding": 20,
   "contributors": {
     "AMSCamacho": "Angela Camacho",

assets/data/links.csv

@@ -1,7 +1,7 @@
 title = "The Development Seed Contributor Network"
 author = "Pete Gadomski"
 description = "An interactive visualization of contributors to Development Seed code and their connections to other repositories"
-central_repository = "developmentseed/DevSeed Team"
+organization_name = "Development Seed"
 repositories = [
     "developmentseed/titiler",
     "developmentseed/lonboard",

assets/data/repositories.csv

@@ -74,7 +74,7 @@ <h1><span id="title-repo-name" class="central-repo">...</span></h1>
         // ─── Load configuration ───────────────────────────────────
         // In production, config.json is generated by the build command from config.toml.
         // For local development, place a config.json in assets/data/ with at minimum:
-        //   { "central_repository": "owner/repo", "contributor_padding": 20, "contributors": {} }
+        //   { "organization_name": "My Org", "contributor_padding": 20, "contributors": {} }
         const configResponse = await fetch('assets/data/config.json');
         if (!configResponse.ok) {
             document.getElementById("chart-container").innerHTML =
@@ -83,7 +83,7 @@ <h1><span id="title-repo-name" class="central-repo">...</span></h1>
         }
         const config = await configResponse.json();
 
-        const REPOSITORY = config.central_repository;
+        const organizationName = config.organization_name || 'Development Seed';
         const contributor_padding = config.contributor_padding || 20;
 
         // Build contributor lookup maps from config
@@ -94,8 +94,7 @@ <h1><span id="title-repo-name" class="central-repo">...</span></h1>
         });
 
         // ─── Populate page from config ────────────────────────────
-        const repoDisplayName = REPOSITORY.includes('/') ? REPOSITORY.split('/').pop() : REPOSITORY;
-        document.getElementById("title-repo-name").textContent = repoDisplayName;
+        document.getElementById("title-repo-name").textContent = organizationName;
         if (config.title) document.title = config.title;
         if (config.description) document.getElementById("chart-description").textContent = config.description;
 
@@ -118,14 +117,12 @@ <h1><span id="title-repo-name" class="central-repo">...</span></h1>
 
         const contributorNetworkVisual = createContributorNetworkVisual(
             container,
-            REPOSITORY,
             contributor_padding,
             masterContributors,
             displayNameToUsername
         )
             .width(size)
-            .height(size)
-            .repository(REPOSITORY);
+            .height(size);
 
         // ─── Load CSV data and render ─────────────────────────────
         const promises = [
@@ -183,15 +180,9 @@ <h1><span id="title-repo-name" class="central-repo">...</span></h1>
                 // Render the visualization
                 contributorNetworkVisual(values);
 
-                // Display most recent commit date
+                // Display most recent commit date across all links
                 let formatDateLong = d3.utcFormat("%B %-e, %Y");
-                let links_to_central = values[2].filter(d => {
-                    if (typeof d.target === 'object' && d.target && d.target.data) {
-                        return d.target.data.repo === REPOSITORY;
-                    }
-                    return d.repo === REPOSITORY;
-                });
-                let most_recent_commit = d3.max(links_to_central, d => +d.commit_sec_max);
+                let most_recent_commit = d3.max(values[2], d => +d.commit_sec_max);
                 if (most_recent_commit) {
                     let commitDate = new Date(most_recent_commit * 1000);
                     document.getElementById("last-commit-date").innerHTML =