feat: add dashboard budget governance contract

[huangruiteng]

Summary

• add a public dashboard budget/governance contract that maps quota, scheduler, todo, run, and evidence fields to operator-facing concepts
• render a Budget & Governance panel in the frontstage dashboard from goal_channel_projection quota/source fields
• extend the sample projection and route smoke anchors for cadence, pause policy, no-spend, and evidence-audit semantics

Validation

• npm run smoke:frontstage-route
• npm run build
• git diff --check
• loopx check --scan-path docs/dashboard-budget-governance-contract.md --scan-path docs/README.md --scan-path docs/product/frontstage-dashboard-interaction-baseline.md --scan-path apps/dashboard/src/data/goal-channel-frontstage.ts --scan-path apps/dashboard/src/views/frontstage-page.tsx --scan-path apps/dashboard/smoke/frontstage-route-smoke.ts

Note: loopx check reports the existing duplicate index rows warning for loopx-meta: raw=5356 unique=5352.

[huangruiteng]

Findings: none.

Validation:

• npm --prefix apps/dashboard run smoke:frontstage-route
• npm --prefix apps/dashboard run build
• git diff --check origin/main...HEAD
• loopx check --scan-path docs/dashboard-budget-governance-contract.md --scan-path docs/README.md --scan-path docs/product/frontstage-dashboard-interaction-baseline.md --scan-path apps/dashboard/src/data/goal-channel-frontstage.ts --scan-path apps/dashboard/src/views/frontstage-page.tsx --scan-path apps/dashboard/smoke/frontstage-route-smoke.ts

Note: loopx check only reports the existing duplicate index rows warning for loopx-meta; the public/private scan is clean. Decision: approved for self-merge. GitHub would not let this account approve its own PR, so I am recording the maintainer review here before merge.