docs(changelog): complete 3.8.6 notes (#281, #361 R2, #423, #615)

The 3.8.6 entry predated the R2/#361 work, #281 and the CodeBuddy merge.
Add the Added/Changed sections (CodeBuddy #423, structure_first cold
reads, net-of-injection gain, faithful bench arm, suspect-file fidelity,
proxy build/test protection + vendor-prefix classification, pi
routeShell) and the #281 hooks-layer auto_update_mcp fix.

Co-authored-by: Cursor <cursoragent@cursor.com>

lean-ctx v3.8.5

test(paths): gate #401 paths-array test on a live PathJail

CI runs `cargo test --all-features`, which enables the `no-jail` feature.
That compiles PathJail out, so `resolve_tool_paths` resolves every path and
the new `explicit_unresolvable_paths_array_errors` test never saw the
out-of-scope rejection it asserts — failing the "Run tests" step on every
release builder.

Gate the test with `#[cfg(not(feature = "no-jail"))]`, matching the existing
PathJail unit tests in `core::pathjail`, and drive it with an absolute path
whose only existing ancestor is `/` so the jail decision is deterministic and
independent of allow-list state left behind by other tests. The test still
runs (and passes) under the default feature set, giving real #401 coverage.

Co-authored-by: Cursor <cursoragent@cursor.com>

fix(windows): platform-stable graph paths + budgeted shell hint

Two Windows-only CI failures behind one release:

- Property-graph node keys were built with native separators, so
  impact_analysis("Models/Engine.cs") matched nothing on Windows. The
  builder now stores canonical `/` paths (determinism, #498) and the
  graph queries normalize native input, so both spellings work.
- The #579 instruction budget did not account for the Windows-only
  SHELL: hint. The hint is condensed (45->21 tok for the POSIX variant)
  and the budget test grants an explicit, guarded 25-token allowance on
  Windows instead of failing the cap by 4 tokens.

Co-authored-by: Cursor <cursoragent@cursor.com>

chore(release): v3.8.2

Co-authored-by: Cursor <cursoragent@cursor.com>

release: v3.8.1 — Field-Report Patch

Co-authored-by: Cursor <cursoragent@cursor.com>

release: v3.8.0 — Governance & Proof

Policy packs with cryptographic decision logs, evidence bundles with
ed25519-signed run manifests, the ctxpkg registry client, CGB v1.0-draft
self-assessment (C2), LoCoMo memory benchmark harness, FinOps cost
attribution, custom embedding models, the four-jobs dashboard redesign,
P0/P1 security hardening and 100+ further improvements.

Co-authored-by: Cursor <cursoragent@cursor.com>

chore(release): 3.7.5 — Web & Research (ctx_url_read) + #361/#362/#363

- ctx_url_read web/research layer: web pages, PDFs and YouTube → compressed,
  citation-backed context (facts/quotes with confidence + source, SSRF-guarded).
- fix #363: background scans never hydrate cloud placeholders (OneDrive/iCloud).
- fix #362: proxy accepts OpenAI-compatible provider keys on loopback routes.
- fix #361: Pi MCP bridge on by default, every read cached through it.

Bump rust/Cargo.toml, lean-ctx-bin, pi-lean-ctx to 3.7.5.

Co-authored-by: Cursor <cursoragent@cursor.com>

lean-ctx VS Code extension 0.1.0