feat: add whats-new review feed

[darron]

Add a derived, read-only review feed over local SQLite so CLI, HTTP, and MCP callers can review newly imported, updated, enriched, failed, or blocked evidence after a timestamp or continuation cursor. The feed normalizes event timestamps to UTC, uses deterministic cursor pagination, supports imports/enrichments/failures filters, and preserves empty arrays in structured JSON output.

Expose the feed as dbrain whats-new, GET /api/whats-new, and MCP dbrain_whats_new. Keep the default events view for raw pipeline chronology and add view=entities for compact item/source groups with preferred summaries, collapsed event kinds, actionability, importance, and compact event refs.

Add migration 11 with review-feed timestamp indexes for items, sources, feed entries, and item enrichments, and align fresh database schema creation with upgraded databases. Update command, MCP, README, route-capability, changelog, and dbrain MCP skill docs around the new agent review workflow.

Behavior changes:

• adds a new root CLI command and authenticated web API route
• adds a new read-only MCP tool with explicit output schema
• opens the CLI store normally so review-feed indexes/migrations can apply
• rejects ambiguous date-only since values and unknown type/view filters
• requires exactly one of since or cursor on all surfaces

Risks:

• this is a derived read-side feed, not a durable activity log, so it can only surface events with trustworthy existing timestamps
• view=entities pagination is still event-based, so multi-page callers must de-duplicate entity rows by entity_key
• review importance and actionability are deterministic hints, not filtering or ranking authority

Follow-ups:

• consider a durable review_events table if derived unions become ambiguous or too expensive
• add agent ack/claim state, watchlists, sync cursor output, or a web review UI only after the v1 feed proves stable
• add categorization events once categorization writes trustworthy timestamps

Closes #54

[github-actions]

PR Diff Stats

PR #55 changed 32 file(s), with +4,197 / -15 (4,212 changed lines).

Bucket	Files	Additions	Deletions	Changed
Docs	8	+1,188	-12	1,200
Tests	5	+1,309	-1	1,310
Migrations	1	+8	-1	9
Generated	0	+0	-0	0
Lockfiles	0	+0	-0	0
Config / Ops	0	+0	-0	0
Code	18	+1,692	-1	1,693
Total	32	+4,197	-15	4,212

Largest Changed Files

File	Bucket	Additions	Deletions	Changed
docs/whats-new.md	Docs	+1,078	-0	1,078
internal/store/review_events_test.go	Tests	+768	-0	768
internal/store/review_events_sql.go	Code	+263	-0	263
internal/store/review_events_group.go	Code	+239	-0	239
internal/mcpserver/server_test.go	Tests	+220	-0	220
internal/app/whats_new_output.go	Code	+193	-0	193
internal/store/review_events_scan.go	Code	+160	-0	160
internal/app/app_test.go	Tests	+152	-1	153
internal/store/review_events_types.go	Code	+144	-0	144
web/server_test.go	Tests	+142	-0	142

Bucket rules

• Docs: Markdown/text docs such as docs/**, README.md, and other *.md or *.txt files
• Tests: *_test.go, test/, tests/, e2e/, and JS/TS *.test.* or *.spec.* files
• Migrations: schema migration/init files such as internal/store/migrations.go and internal/store/schema_init.go
• Generated: local runtime/generated surfaces such as data/, logs/, tmp/, vault/, and web/ui/dist/
• Lockfiles: dependency lockfiles such as go.sum and package-lock.json
• Config / Ops: CI, config, packaging, skills, deploy, and scripting files such as .github/, packaging/, skills/, scripts/, Makefile, Dockerfile, Taskfile.yml, config.yaml.sample, and fly.toml
• Code: everything else