release: prepare v1.2.0-alpha.1 and record rollout blockers

RELEASE_NOTES.md

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+# v1.2.0-alpha.1
+
+Experimental pre-push security safety net for AI-accelerated development. Python package
+version: `1.2.0a1`. This alpha is **not a rollout GO**; no real hook capability is enabled.
+
+- Analyze immutable pushed commits across refs without changing the working tree or
+  replacing existing hooks. Share one deadline across preparation, analysis and reporting.
+- Keep the existing ranker responsible for scope and physically exclude vendor code from
+  graph inputs. Reuse only compatible, complete immutable graph and answer artifacts.
+- Gate advisory and blocking alerts on the same actionable change/witness/repair evidence.
+  Preserve explicit incomplete coverage; optional model assistance cannot create evidence.
+- Add frozen runtime and PHP/Node/Python evaluation records with honest populations,
+  missing-target accounting and versioned eligibility that rejects stale evidence.
+- Repair the pinned JavaScript frontend's Gruntfile omission and incomplete-census handling.
+  The real NodeGoat input now retains 44/44 files; native PHP/JavaScript smoke passes.
+
+Implementation verification: 1321 tests passed, nine skipped; detector/map/local-pair
+gates and packaged partition smoke passed. These checks verify implementation contracts,
+not useful hook precision, recall or latency.
+
+Rollout remains blocked by representative changed-code latency/completion, VAmPI
+query/context/transitive evidence and independent reviewed per-capability populations.
+The earlier eligibility artifact is stale under the repaired identities and enables
+nothing. See [current spec status](https://github.com/norandom/OpenUltraSAST/blob/v1.2.0-alpha.1/.kiro/specs/pre-push-safety-net/status.md) for the
+owners, unchanged thresholds and required revalidation. Pre-push implementation stands
+at 26/27 tasks; task 8.3 remains blocked. C arithmetic/bounds detection is unsupported.