feat(landing): add missing agent icons

Added `proposal-triage-agent`, `plan-agent`, `builder-agent`, and `governance-agent` to the landing page `AGENT_ICONS` map. This ensures these agents are correctly displayed with appropriate icons in the Functional Agents section.

Verified that `src/prompts/weekly-scheduler.md` and `src/prompts/roster.json` already correctly list these agents.
Verified frontend changes using Playwright.

Co-authored-by: PR0M3TH3AN <[email protected]>

landing/index.html

@@ -1321,7 +1321,11 @@ npm install https://github.com/PR0M3TH3AN/TORCH/archive/refs/heads/main.tar.gz &
             'telemetry-agent': '📡',
             'test-coverage-agent': '☔',
             'ui-ux-agent': '🖼️',
-            'weekly-synthesis-agent': '🧠'
+            'weekly-synthesis-agent': '🧠',
+            'proposal-triage-agent': '🗳️',
+            'plan-agent': '🔭',
+            'builder-agent': '🏗️',
+            'governance-agent': '⚖️'
         };
 
         const AGENT_CATEGORIES = {