docs: resync skills with smg HEAD (v1.5.0)

[slin1237]

Problem

The SMG development skills were last verified against smg on 2026-06-08. Since then ~123 commits have landed in the smg codebase (now v1.5.0), leaving the skills with stale crate names, removed subsystems, drifted APIs, and file.rs:NNN line references that no longer match.

Solution

Audited all 24 skill files against smg HEAD by reading the current source (not commit messages — e.g. a "rename least_load" commit was misleading; the policy still exists and the count was correct). Fixed every factual drift, added coverage for new subsystems, and de-brittled all file.rs:NNN references to file.rs + symbol-name anchors so they survive smg's churn.

Changes

Removed / renamed (factual fixes)

• map/SKILL.md — drop removed tui/smg-tui crate; add new mock_worker crate; fix repo-root layout line; Router params ~80→~110; broaden discovery-DAG steps path.
• implement/SKILL.md — drop removed Terminal UI/tui/ row.
• mcp-feature.md — drop removed oauth.rs from the module map.
• observability-feature.md — drop removed /ws/metrics WebSocket; document new runtime_metrics.rs.
• tenancy-feature.md — drop removed TenantAliasStore/resolve_tenant_key (resolution now infallible); note new request_charge_id field.
• routing-policy.md — get_all_power_of_two_policies()→get_all_load_aware_policies(); add remove_worker.
• rate-limit-feature.md — middleware/scheduler.rs→middleware/scheduler/; correct with_admission_layer.
• config-plumbing.md — rewrite Step 4 to the real &self builder / struct-literal shape.
• storage-backend.md — data-connector v2.2.0→v2.3.0.
• contribute/SKILL.md — clippy gate --workspace; add std::process::exit disallowed-method; clarify generate-clients scope.

New coverage

• provider-api.md — shared SSE codec (SseEncoder/SseDecoder) + protocol fidelity (serde flatten, function_call pairing).
• grpc-backend.md — 4th macro impl_admin_ops!, per-engine macro matrix, TokenSpeed engine, get_loads/subscribe_kv_events, DP-rank pinning.
• kv-index-feature.md — fused match_and_insert; removal of the 2048-worker cap.
• mesh-feature.md — MeshAdapters composition root + outbound worker mesh sync; watermark op-id tie-break.
• multimodal-feature.md — ABI-generalization renames (VisionPreProcessor, PreprocessedEncoderInputs, …) + first-class video modality.
• mcp-feature.md — BuiltinToolType builtin-tool classification.
• discovery-feature.md — kv_engine_id special key + tokenspeed backend.
• reasoning-parser.md — find_pooled_parser_for_model→create_for_model; QwenThinkingParser example.
• tool-parser.md — MiniMax-M2 schema coercion / unknown-name forwarding.
• bindings-update.md — PolicyType↔PolicyConfig sync callout.
• review-pr/SKILL.md — note routers now include responses/, conversations/, grpc/.

Durability — all recipes: file.rs:NNN line refs replaced with file.rs + symbol anchors.

scheduler-feature.md and auth-feature.md were verified accurate (de-brittling only / no change). commands/smg.md, .agents/, and plugin configs are unchanged. No skill description: frontmatter changed, so triggering behavior is unaffected.

Affected Skills

• smg:map
• smg:contribute
• smg:review-pr
• smg:implement
• Recipe files (all under skills/implement/)
• Command router (smg.md) — verified, unchanged
• Plugin config (plugin.json) — unchanged

Checklist

• Follows conventional commit title format
• Commit(s) are signed off (git commit -s)
• Tested with claude plugins add . locally — not run; all content verified against smg HEAD by reading source, and the 11 most load-bearing new symbols confirmed at their cited paths
• Skill triggers correctly on intended prompts — no description: frontmatter changed, so triggers are unaffected
• No broken @file.md references in skills