[JOI-6/15] feat(server): add Friction Log API, CLI and MCP

[salmonumbrella]

What changed

• Exposes Friction Log digests, findings, and recurring patterns through HTTP, CLI, and read-only MCP tools.
• Adds agentsview friction run to build missing completed days on demand, with date, rebuild, and dry-run options.

Why

The daily review is stored after PR05, but users and integrations still need a way to read it and request a catch-up run. These surfaces use the same stored data rather than separate review logic.

Usage

Run agentsview friction digest for the latest Markdown digest, agentsview friction findings for session findings, agentsview friction patterns for recurrence, or agentsview friction run to build missing days. HTTP and MCP clients can read the same results.

Part 6 of 15 in the stacked Friction Log series. Depends on #1935. GitHub shows the cumulative diff against main; review the PR06-only diff. Merge PR05 first. Refresh this branch against main and confirm its diff is scoped to PR06 before merging.

Refs #1908

[roborev-ci]

roborev: Combined Review (0d0343f)

Verdict: Changes require fixes for 1 finding.

Medium

• internal/friction/review/runner.go:418-423: Runner.CatchUp treats the maximum stored digest date as a contiguous watermark, so building a later complete day first can cause an earlier missing date in the backfill window to be skipped permanently. Iterate the bounded backfill range and skip only dates that already have a digest, or maintain and query a contiguous watermark. Add a regression test covering a later date built before an earlier missing date.

  Reported by: codex

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Reviewers: 2 done | Synthesis: codex, 5s | Total: 20m45s