fix(compat): close semantic lineages and remediate recovery

[pablontiv]

What

• Replace textual/checksum lineage matching with conservative semantic schema identity keyed by (AppliedVersion, Signature).
• Separate schema_migrations provenance from semantic hashing while preserving ledger validation and migration planning.
• Require every physical catalog fixture to migrate losslessly through production OpenCompatible to the exact current head with zero skips.
• Classify recover as remediation: retain the mutation-grade startup lease while bypassing ordinary compatible-open and pre-handler sync.

Why

ALTER-built V13 databases produced valid but unrecognized V14 signatures, causing every operational command—and recover --dry-run itself—to fail with unsupported_lineage/migration_failed.

This closes the defect class rather than adding V14-specific signature exceptions.

Closes #58.

How

• Added token-based DDL canonicalization that removes formatting/comments while preserving literals, quoted identifiers, constraints, expressions, triggers, indexes, and virtual-table configuration.
• Added collision-safe composite catalog lookup and deterministic current-head selection.
• Regenerated semantic signatures without editing fixture SQL or migration V1–V14 bodies.
• Replaced skipped lineage coverage with a 19-fixture V1→V14 closure matrix, including both ALTER-built histories.
• Added explicit remediation startup classification, immediate/busy-owner lease tests, real ALTER-built recovery dry-run immutability, and repeated subprocess contention coverage.
• Updated living documentation and ADRs 0004–0006.

Verification

• TestEveryCatalogFixtureReachesCurrentSemanticHead: 19/19 fixtures PASS, zero skips.
• ALTER-built recover --dry-run: PASS; no circular diagnostics; DB and empty WAL unchanged.
• Real affected database smoke: PASS on an online SQLite .backup; original database hash unchanged.
• Remediation contention: PASS with -count=5; sync counter remains exactly 1.
• Windows internal/startuplock compile: PASS.
• just ci: PASS, aggregate coverage 86.1%.
• Independent task reviews and final whole-branch review: PASS.

No new flag, command, lock type, fallback catalog, repair mode, persistent application state, V14 runtime exception, or migration SQL change was added.

Checklist

• Tests pass (just test)
• Code is clean (just check)
• Snapshots updated if needed (cargo insta review) — not applicable
• Changes are documented if user-facing