Release camelCase contract surface for 0.12.0

[IslamBaraka90]

Everything for the 0.12.0 release, in two commits.

No algorithms were added or removed: 324 topics before, 324 after. What changes
is the surface in front of them.

Breaking

• 23 entry points renamed snake_case → camelCase (bollinger_bands →
  bollingerBands, true_range → trueRange, double_top → doubleTop, …).
• 110 sibling re-exports removed across 28 subpaths. .../momentum/rsi no
  longer re-exports williamsR, connorsRsi, stochasticRsi or
  ultimateOscillator — a subpath is one function, and the symbol did not
  disappear, it stopped being in more than one place.
• Payload schema 1.0.0 → 2.0.0. Per-topic languages is now
  catalogLanguages.

Both code-level tables are in CHANGELOG.md, generated by diffing the published
0.11.0 payload rather than hand-typed.

Added

• CommonJS can resolve the package. Every entry in the exports map now
  declares a require condition alongside import, both pointing at the same
  ES module. CommonJS consumers were failing at resolution, not loading —
  import is not a condition require() matches — so there is no second build,
  the tarball is the size it was, and a dual-package hazard is impossible.
  Refs Support for CommonJS / dual module exports #1.
• The payload describes the surface that serves it. package now states the
  runtime facts an agent previously had to infer (type, engines, root export
  is metadata-only, algorithms are subpath-only) and names the machine surface:
  /llms.txt, /version.json, /reference/payload.json, and the per-domain and
  per-topic route patterns. Every route was requested against the live site
  before being written down.
• archetypes, the five input shapes as data — derived counts, the canonical
  TypeScript input type, a minimal payload that executes, and the validator to
  run at the boundary. The machine half of /guides/archetypes/.
• domains[].slug, so a domain's URL is no longer rediscovered by finding
  one of its topics and splitting its path.
• CHANGELOG.md, which also ships inside the tarball.

Improved

	0.11.0	0.12.0
Topics with a validated api contract	280 / 324	324 / 324
Topics with a fixture-verified worked example	88	158
Topics with any worked example	279	324

Guardrails

• gen-docs.mjs takes --strict-contracts and refuses to emit when a topic has
  no api: block; CI additionally asserts coverage over the committed payload,
  so it runs on every pull request whether or not the catalog checkout is
  available. Coverage that nothing enforced is how a complete 271/271 quietly
  became 280/324.
• The generator refuses to emit a payload whose own structure is inconsistent —
  a domain spanning two path roots, or an archetype with no description.
• CI and the release workflow both smoke-test the packed tarball from CommonJS
  as well as ESM, against a clean consumer install.

Validation

• npm run verify — 493/493 tests.
• docs.json byte-identical on re-run; gen-docs.mjs --check --strict-contracts
  passes.
• Packed tarball installed into a clean consumer and imported from both ESM and
  CommonJS.
• All four archetype examples executed against the built package. Two of them
  caught real errors in the published guide's snippets, which are corrected in
  the payload.

Known issue, unrelated to this branch

npm run sync currently fails: the catalog has grown a family of ten topics
that share one calculate() dispatcher, and sync refuses to emit until each has
its own entry point. Nothing in this branch depends on resolving that — the
registry is unchanged at 324 topics, and docs.json regenerates from it — but
the exports map could not be produced by re-running sync. It was rewritten in
place instead and then checked against what the updated generator produces for
the same 324 paths, so the next successful sync is a no-op on package.json.