[milestone Milestone 12] `internal/otel` — Extended observability: add SMT solver metrics (`solver_dura...

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🤖 Auto-filed from milestone doc bullet.

Repo: WasmAgent/symkernel
Milestone: Milestone 12 — Advanced Symbolic Reasoning & Z3 Integration (Phase 2)
Bullet:

internal/otel — Extended observability: add SMT solver metrics (solver_duration_ms, sat/unsat/unknown counts, constraint_complexity_score) and cache hit/miss telemetry; export Prometheus metrics at /metrics

Relevant code context (from worktree)

file: internal/otel/otel_test.go
file: internal/otel/otel.go
new (does not exist yet): sat/unsat/unknown
new (does not exist yet): hit/miss
new (does not exist yet): /metrics
contains 'internal': ""/tmp/tmp.ufhVOKX3Uq"/wasmagent-js"/packages/claude-agent-sdk/src/memory.ts
contains 'internal': ""/tmp/tmp.ufhVOKX3Uq"/wasmagent-js"/packages/compliance/src/repair/RepairPlanner.ts
contains 'internal': ""/tmp/tmp.ufhVOKX3Uq"/wasmagent-js"/packages/cloudflare-worker/src/CloudflareWorkflowEngine.ts
contains 'extended': ""/tmp/tmp.ufhVOKX3Uq"/wasmagent-js"/packages/core/src/agents/verifiers/ScalarLLMJudgeVerifier.ts
contains 'extended': ""/tmp/tmp.ufhVOKX3Uq"/wasmagent-js"/packages/core/src/models/types.ts
contains 'extended': ""/tmp/tmp.ufhVOKX3Uq"/wasmagent-js"/packages/core/src/evals/index.ts

Implementation note: Files marked "new (does not exist yet)" must be created from scratch. verify-first should return PROCEED (not NOT_YET) — there is no prerequisite blocking this work.

Acceptance criteria

• Command go build ./... passes
• The specific work described in the bullet above is implemented in the smallest number of files required.
• No unrelated files touched (git status --short output limited to the intended change).

Notes for the implementer

This issue was auto-created by SweepMilestoneBulletToIssue. The bullet text is verbatim
from the milestone doc. If ambiguous or too large for a single implement cycle,
verify-first should return NEEDS_SPLIT with sub-issue proposals or NEEDS_HUMAN with the blocker.

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Filed automatically.