feat(FN-2989): merge fusion/fn-2989

- Add `CustomProviderForm` component and routing for user-defined OpenAI/Anthropic-compatible endpoints (FN-2987)
- Expand `agent-heartbeat.ts` with richer prompt guidance and criteria updates
- Strengthen executor prompts in `executor.ts` with expanded implementation guidance
- Enrich reviewer prompts in `reviewer.ts` with enhanced review criteria
- Add triage prompt guidance in `triage.ts` for task classification
- Extend merger prompts in `merger.ts` with merge strategy guidance
- Add `agent-document-tools.test.ts` and `agent-tools.test.ts` integration tests
- Expand `store.ts` with new task/document operations; add `task-documents.test.ts` and `store.test.ts`
- Add legacy API route in `dashboard/app/api/legacy.ts` and auth path routing
- Update `ModelOnboardingModal` with custom provider onboarding flow
- Extend `SettingsModal` with custom provider configuration UI and mobile layout tests
- Add changeset for `@runfusion/fusion` minor release

Commits merged:
- feat(FN-2989): complete Step 5 — enrich remaining agent prompts
- feat(FN-2989): complete Step 4 — enrich reviewer prompt criteria
- feat(FN-2989): complete Step 3 — strengthen triage prompt guidance
- feat(FN-2989): complete Step 2 — expand executor guidance prompts
- feat(FN-2989): complete Step 1 — expand heartbeat prompts
- feat(FN-2987): merge fusion/fn-2987
- feat(FN-2959): merge fusion/fn-2959-2

Files changed:
.changeset/custom-openai-anthropic-providers.md    |   5 +
 docs/task-management.md                            |   4 +
 packages/core/src/__tests__/store.test.ts          |  38 +++
 packages/core/src/__tests__/task-documents.test.ts |  32 +++
 packages/core/src/store.ts                         |  34 ++-
 packages/dashboard/app/api/legacy.ts               |  41 ++++
 .../app/components/CustomProviderForm.css          |  45 ++++
 .../app/components/CustomProviderForm.tsx          | 203 ++++++++++++++++
 .../app/components/ModelOnboardingModal.css        |  14 ++
 .../app/components/ModelOnboardingModal.tsx        |  62 ++++-
 .../dashboard/app/components/SettingsModal.css     |  38 +++
 .../dashboard/app/components/SettingsModal.tsx     |  91 +++++++-
 .../__tests__/CustomProviderForm.test.tsx          |  60 +++++
 .../__tests__/ModelOnboardingModal.test.tsx        |  23 ++
 .../components/__tests__/SettingsModal.test.tsx    |  13 ++
 .../__tests__/SettingsModalNodeRouting.test.tsx    |   4 +
 .../components/__tests__/settings-mobile.test.tsx  |   4 +
 packages/dashboard/src/auth-paths.ts               |   4 +
 packages/dashboard/src/routes.ts                   |   2 +
 .../__tests__/custom-provider-routes.test.ts       | 118 ++++++++++
 .../src/routes/register-custom-provider-routes.ts  | 254 +++++++++++++++++++++
 .../src/__tests__/agent-document-tools.test.ts     |  15 ++
 packages/engine/src/__tests__/agent-tools.test.ts  |  43 ++++
 packages/engine/src/agent-heartbeat.ts             | 107 +++++++--
 packages/engine/src/agent-reflection.ts            |   7 +-
 packages/engine/src/agent-tools.ts                 |  28 ++-
 packages/engine/src/cron-runner.ts                 |   4 +
 packages/engine/src/executor.ts                    |  69 +++++-
 packages/engine/src/merger.ts                      |  26 ++-
 packages/engine/src/mission-execution-loop.ts      |   6 +
 packages/engine/src/reviewer.ts                    |  24 ++
 packages/engine/src/step-session-executor.ts       |  11 +-
 packages/engine/src/triage.ts                      |  20 ++
 33 files changed, 1407 insertions(+), 42 deletions(-)

Fusion-Task-Id: FN-2989

packages/engine/src/cron-runner.ts

@@ -631,6 +631,10 @@ const AI_AUTOMATION_SYSTEM_PROMPT = [
   "You have read-only access to the project files.",
   "Execute the prompt precisely and return concise, structured results.",
   "When analyzing code or data, provide actionable summaries.",
+  "Structure outputs with clear sections: Summary, Findings, Recommended Actions, and Risks/Unknowns when applicable.",
+  "Actionable summaries must include concrete next steps, affected areas, and impact level.",
+  "If errors occur (missing files, command failures, ambiguous input), report them clearly with probable cause and what was attempted.",
+  "If no notable findings exist, state that explicitly and keep output brief rather than inventing issues.",
 ].join("\n");
 
 /**