feat: add bounded SQL language intelligence

[Light2Dark]

Summary

Final stacked overhaul PR. Depends on #205.

• adds revision-safe diagnostics, hover, definition, references, highlights, rename, document symbols, folding, formatting, and code-action provider contracts
• composes providers concurrently under one absolute deadline with per-provider cancellation, hostile-result validation, aggregate budgets, source reports, and explicit truncation evidence
• adds parser-free statement symbols/folding and table-function relation completion
• exposes all feature tasks through the CodeMirror editor lifecycle without coupling core to DOM presentation
• adds deterministic fuzzing, a mutation pilot, 50-session disposal evidence, feature latency gates, a packed marimo-shaped runtime fixture, and Chromium/Firefox/WebKit CI
• records the measured core bundle change and enforced ceilings in ADR 0007

Validation

• 1,835 unit tests
• coverage: 97.65% statements, 96.27% branches, 99.43% functions, 97.91% lines
• changed-code coverage against feat: add bounded semantic SQL completion #205 head: every changed production file above 95%
• 7 performance gates
• mutation pilot killed
• 18 Chromium browser tests; Firefox and WebKit added to CI
• typecheck, oxlint, test integrity, demo build, packed package/SSR/marimo fixture, and worker placement pass
• core: 57,307 gzip / 215,639 raw bytes within 57 KiB / 212 KiB ceilings
• worker aggregate: 168,218 gzip / 741,480 raw bytes within 165 KiB / 725 KiB ceilings

Exactly two final adversarial reviewers audited the implementation. All findings were fixed and both reviewers report no remaining findings. No additional Copilot review was requested.

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Summary by cubic

Adds bounded SQL language intelligence to the language service and CodeMirror adapter: diagnostics, hover, navigation, rename, symbols, folding, formatting, and code actions. Introduces a revision-safe, deadline-bound provider runtime with cancellation, validation, normalized results, docs (ADR 0007), and CI gates.

• New Features

  • Unified language features on sessions and the editor with one revision/cancellation model.
  • Concurrent provider composition with a single budget (featureProviderBudgetMs), per‑provider abort, hostile‑result validation, source reports, and explicit truncation evidence.
  • Parser‑free statement symbols/folding and completion support for table‑valued functions (catalog boundary and ranking updated).
  • Exported APIs and bounds (MAX_SQL_FEATURE_RESULTS, MAX_SQL_FEATURE_TEXT_LENGTH) with normalized results.
  • Hardening: deterministic fuzzing, mutation pilot (in CI), performance gates, updated bundle ceilings (core 57 KiB gzip/212 KiB raw; worker 165 KiB gzip/725 KiB raw), and multi‑browser CI (Chromium/Firefox/WebKit).

• Migration

  • Optional: register providers via featureProviders (and optionally configure featureProviderBudgetMs) when creating the service; no changes needed to existing completion setups.
  • Use new session/editor tasks (e.g., diagnostics(), hover(), definitions(), rename(), documentSymbols(), foldingRanges(), format(), codeActions()).

^{Written for commit e5bee95. Summary will update on new commits.}