release: cut the merged fix wave as v0.2 #23

Goal

Cut the merged fix wave as http-sql v0.2: one commit flips the version everywhere, so the document stops contradicting its own wire version.

The wave includes additive changes S11 assigns to a minor bump (the unsupported_media_type registered code) AND subtractive MUSTs S11 does not cover (sequential non-atomic execution + REQUIRED statementIndex from #1; tagged-value emission from #2) that make previously-conforming servers non-conforming. Landing all of it labeled 0.1 is self-contradiction; the per-item (v0.2+) markers from PR #20 were an interim measure pending this release decision, now ruled: the wave IS v0.2.

Requirements

Behavior

• SPEC.md: every self-reference to the current version reads v0.2 (title area, S9 example header, S10.1 conformance preamble); S11 gains a two-line version history (0.2: what changed, one sentence; 0.1: initial).
• conformance/README.md: suite preamble says v0.2; the (v0.2+) marker on R-4 and its explanatory preamble sentence are removed (the whole suite is v0.2 now).
• Examples: VERSION constants and X-Http-Sql-Version literals flip to 0.2 in reference-server.ts, both Cloudflare servers, and the reference client's accepted version if it pins one.
• implementations.md / README.md: spec references read v0.2.
• Coherence read of merged SPEC.md 6.1/S7/S10.1 after the nine-branch wave: no stale cross-references, lastInsertId bullet is the narrowed string-or-null form.

Error Handling

• CI spec-sanity green (structure headings unchanged by the flip).

Done When

• grep for "0.1" across SPEC.md, conformance/, examples/ returns only historical/changelog mentions
• PR merged

This issue is complete when: a server advertising X-Http-Sql-Version: 0.2 is what the spec, conformance suite, and all three reference servers describe.