docs(contributor): refresh task board for v0.5.2 and current seams

[huangruiteng]

Summary

Refresh the public contributor task board (docs/development/contributor-tasks.md) against current main state:

• Bump release state to v0.5.2 (v0.4.9, v0.5.0, v0.5.1, v0.5.2 landed), explicit installation ownership (feat(update): make installation ownership explicit #3566), and extension-doctor readiness recovery (Recover extension doctor readiness across LoopX releases #3556). GH-C04 now tracks docs through v0.5.2 and the v0.1.3–v0.5.2 timeline.
• Archive shipped rows: GH-C16 (public native Goal trajectory summaries, feat(benchmark): publish public native Goal trajectory summaries #3327), GH-C68 (scheduler ACK decision tables, test(scheduler): migrate ACK rules into decision tables #3288), GH-C86 (per-goal token/cost/duration dashboard, feat(quota): per-goal token/cost/duration capture + dashboard surfacing #3117), GH-C94 (completion_turn_key projection, fix(todos): preserve completion_turn_key in event-sourced projection #3206).
• Refresh claim state: GH-C02 claim issue lapsed (back to Available); GH-C47 is now under review via the Pi loopx_task_lease facade (feat(pi): expose explicit task lease facade #3559, closing [Task]: Adopt task_lease_v0 in the Pi host integration (GH-C47) #3549).
• Add GH-C99 (deterministic four-arm study contract / orchestrator runtime provenance fixture) as an Available P1 slice.
• Update Recent Maintainer Progress rows for the TypeScript transaction payoff phase (docs(rfc): enter TypeScript transaction payoff phase #3447), coordination Stage 2 slice (feat(coordination): Stage 2 slice - aggregate head, file provider, claim_work executor #3529), goal-channel auto-notify (feat(goal-channel): default human-gate auto-notify on for new goal channels #3523), benchmark boundary hardening (feat(benchmark): fail closed on runtime closeout drift #3503–feat(benchmark): add provider-neutral four-arm study contract #3516, fix(benchmark): accept namespaced public case ids #3532), heartbeat replay settlement (fix(quota): settle completed heartbeat replays #3578), botmux/desktop-chat routing, and the new quota/control-plane fixes.
• Update Technical Directions and Projection Sources to current seams. No private or local state was copied.

Validation

• git diff --check — clean
• python3 examples/docs-governance-smoke.py — ok
• loopx check --scan-path docs/development/contributor-tasks.md — 0 errors, public boundary clean
• loopx canary premerge --from-git-diff — 8/8 risk smokes + public boundary passed
• Private-marker scan — clean (only sk- false positives from "task-*" words)

Docs-only, single-purpose, public-safe.