Promote CodeStory v0.15.0 to main

[TheGreenCedar]

Context

Closes #1134
Refs #899
Refs #1046
Refs #887
Refs #884

CodeStory v0.15 replaces the grounding/runtime publication, identity, sidecar, retrieval, and managed-platform foundations while keeping local graph navigation available when deep retrieval is unavailable. This PR promotes the accepted integration branch to main; it does not itself claim publication or installed-runtime success.

Promotion goal

Promote dev/codestory-next at 2b85609e39256a3f5271a405c35d19c95b935515 to main for v0.15.0, preserving release ancestry with a merge commit and letting the main-only workflow own signing, notarization, tagging, publication, and post-publish proof.

Included work

• Atomic graph, snapshot, lexical, and retrieval publication with generation-coherent reads and fail-closed recovery.
• Project-scoped identity, process/runtime proof, durable broker/lease coordination, bounded scheduling, and owned cleanup.
• Managed plugin convergence, native package/upgrade proof, cross-platform worktree setup, and staged CI/release evidence.
• macOS 15 support: managed Metal on Apple Silicon and explicit CPU/external policy on Intel, with signed/notarized publication still pending the release workflow.
• Product-facing v0.15 release notes from Polish the v0.15 changelog for release #1132 / PR [codex] polish v0.15 release notes #1133.

Ancestry and tree proof

• main: 3c48262278c5c32dc6ab8c35ea62ddb2afd6ab91 (v0.14.3)
• dev/codestory-next: 2b85609e39256a3f5271a405c35d19c95b935515
• Ancestry before promotion: 0 behind / 190 ahead
• Merge method: merge commit. Do not squash or rebase; the integration branch and release topology are part of the proof.

Verification

• Integration run 29352437957 passed the full source gate, live repo-scale stats, six packaged targets, both Windows managed handoffs, protected Apple Silicon Metal lifecycle, and exact-head closeout on production head 611052bd.
• The only later tree change is CHANGELOG.md; PR [codex] polish v0.15 release notes #1133's exact tree passed full source run 29354827392 and independent release-boundary review.
• python .github/scripts/check-codestory-release.py --version 0.15.0 — synchronized across eight crates, Cargo.lock, and three plugin manifests.
• Versioned 0.15.0 release-note extraction — passed, 87 lines / 5,294 bytes.

Remaining release work

• The main-triggered release must rerun exact-main evidence, build all six assets, sign/notarize both Mac binaries, pass protected Metal, publish archives/checksums, and pass every post-publish cell.
• The marketplace repository must be updated and refreshed, then a fresh Codex installation must prove installed path/version/digest, project status, restart survival, and live packet/search.
• A separate two-phase protected-host reboot bundle remains required; the automated Metal lifecycle does not prove an OS reboot.
• Keep Epic: trustworthy grounding and retrieval from v0.14.3 through v0.15.0 #899, Make macOS a release-gated supported platform #1046, Apple Silicon Metal sidecar needs protected v0.15 acceptance replay #887, and Make CodeStory readiness broker a durable cross-process resource manager #884 open until their publication and live-install evidence passes.