feat(FN-1449): complete agent UI field parity with Agent Companies

This change aligns agent editing surfaces across dashboard UI, API payloads,
and import/template flows so every first-class editable agent field is
round-trippable.

Backend changes:
- Add memory and bundleConfig fields to POST/PATCH /api/agents routes
- Fix agent-companies-parser to use first-class fields (title, icon, role,
  reportsTo, instructionsText) instead of metadata fallbacks
- Update import dry-run preview to show more manifest fields

UI changes:
- Enable identity field editing (name, title, icon, role, reportsTo) in
  AgentDetailView ConfigTab
- Add instruction bundle configuration (mode, entry file, files, external
  path) to ConfigTab
- Add memory field to NewAgentDialog
- Fix AI generation mapping to preserve systemPrompt as instructionsText
- Update AgentImportModal preview to show icon, reportsTo, and instructions

Test fixes:
- Update parser tests for new first-class field behavior
- Add MissionExecutionLoop mock for serve tests

Documentation:
- Add agent field parity matrix to docs/agents.md
- Create changeset for @gsxdsm/fusion

.changeset/fn-1449-agent-ui-parity.md

@@ -0,0 +1,12 @@
+---
+"@gsxdsm/fusion": patch
+---
+
+Complete agent UI editing parity with Agent Companies manifest fields. This update:
+
+- Adds `memory` and `bundleConfig` fields to the agent create/update API routes
+- Fixes Agent Companies manifest parsing to use first-class fields (`title`, `icon`, `role`, `reportsTo`, `instructionBody` maps to `instructionsText`) instead of lossy metadata fallbacks
+- Enables identity field editing (name, title, icon, role, reportsTo) in Agent Detail settings
+- Adds instruction bundle configuration (mode, entry file, files, external path) to Agent Detail settings
+- Adds `memory` field support to New Agent dialog and AI generation mapping
+- Updates Agent Import preview to show more manifest fields (icon, reportsTo, instructions snippet)