[JOI-7/15] feat(frontend): add Friction Log page

[salmonumbrella]

What changed

• Adds the Friction Log page with dated digests, P0 alerts, recurring patterns, findings, spend, Markdown export, and an on-demand build action where the server allows it.
• Links stored findings from the session signal panel and adds Friction Log navigation from Quality.

Why

The API and CLI expose the review, but users need to see what happened on a given day and follow a finding back to the exact session message before acting on it.

Usage

Open Friction Log from the header or /friction. Choose a date, inspect the linked findings, or use Build now for missing completed days. Read-only servers show stored digests without the build action.

Part 7 of 15 in the stacked Friction Log series. Depends on #1936; screenshot asset #1939 supports its docs check. GitHub shows the cumulative diff against main; review the PR07-only diff. Merge PR06 first. Refresh this branch against main and confirm its diff is scoped to PR07 before merging.

Refs #1908

[roborev-ci]

roborev: Combined Review (d8e7902)

Verdict: Changes require fixes for 4 findings.

Medium

• cmd/agentsview/main.go:323: Production sync engines never receive FrictionConfig, so configured seat patterns are parsed and validated but never recorded; disabling friction also stops only the digest runner while findings continue to be computed and persisted. Wire the compiled dimension resolver and enabled flag into every production engine construction path, and gate friction computation and backfill accordingly.

  Reported by: codex

• internal/db/friction_digest.go:85; internal/db/friction_list.go:133: Read-only archives may omit friction tables, but higher-level friction queries directly access them and fail with missing-table errors instead of returning empty results. Apply optional-table capability checks to every friction reader or branch queries when optional tables are absent.

  Reported by: codex

• internal/server/huma_routes_metadata.go:181; frontend/src/lib/components/layout/AppHeader.svelte:98: friction_available depends on a write runner, causing read-only servers with stored digests to hide the Friction Log entirely. Expose separate read and build capabilities; use read capability for navigation and digest reads, and build capability only for review execution.

  Reported by: codex

• internal/service/friction_direct.go:11: directBackend.SupportsFriction always returns true, so PostgreSQL, DuckDB, and ClickHouse paths can advertise friction tools without verified read-table support and fail at runtime. Base capability reporting on verified friction read support and suppress MCP tool registration for unsupported backends.

  Reported by: codex

---

Reviewers: 2 done | Synthesis: codex, 9s | Total: 18m47s