skillscript-runtime v0.15.2

Closes the fourth and final finding from the v0.15.0 cold-adopter Phase 1
dogfood: execute_skill was the only skill_* MCP tool taking
skill_name; the other four (skill_read, skill_metadata, skill_status,
skill_write) all take name. The outlier was historical — execute_skill
needed skill_name to disambiguate from source in the inline-execute
mode — but to a cold adopter hand-wiring JSON-RPC, the inconsistency was
a papercut on every call.

Per Perry signoff (thread 75abc8c0): name is canonical going forward;
skill_name is a silent back-compat alias. No tier-3 advisory, no
deprecation warn. Three arguments for name-canonical:

1. Less drift — 4 of 5 skill_* tools already use name. Aligning one
   outlier is cheaper than migrating four.
2. The source disambiguation argument doesn't generalize — other tools
   don't have a sibling kwarg that could collide.
3. Tool name carries context — skill_read({name}) is unambiguous because
   the tool name says skill; the kwarg need not repeat it.

Surface changes

• execute_skill MCP tool accepts name as canonical; skill_name is
  accepted as a silent alias. If both are supplied with different values,
  the call is rejected as ambiguous. Matching values pass through.
• inputSchema declares both kwargs, with the skill_name description
  explicitly flagging it as a back-compat alias.
• execute_skill(...) function-call grammar (in-skill, src/parser.ts)
  accepts either name= or skill_name=. Parser-time ambiguity check
  mirrors the MCP-wire path.
• dispatchExecuteSkillIntercept (in-skill $ execute_skill dispatch,
  src/composition.ts) accepts either kwarg.
• Composition-reference lint extractor (src/lint.ts) recognizes either
  kwarg form when collecting skill references for the
  unknown-skill-reference rule.
• help-content.ts canonical-shape headers updated to show name= as
  the preferred form; worked examples below stay on skill_name= since
  the alias works unchanged and per-example rewrites add no value.

Scope

Tightly scoped to skill_* per Perry's framing. data_* and file_*
tools have their own naming conventions; if the Phase 2 cold-adopter
dogfood surfaces analogous warts in those families, file separately.
Don't compound scope.

Tests

tests/v0.15.2-execute-skill-name-kwarg.test.ts — 14 new cases covering
MCP-wire dispatch (canonical, alias, identical-result equivalence,
ambiguity rejection, disambiguation preservation, inputSchema shape) +
function-call grammar (canonical works, alias works, conflict rejected
at parse time) + lint extractor (kwarg recognized for both shapes,
unknown-skill-reference fires correctly).

Files changed

• src/mcp-server.ts — executeSkill handler + inputSchema.
• src/parser.ts — function-call kwarg alias.
• src/composition.ts — in-skill $ execute_skill dispatch.
• src/lint.ts — composition-reference regex extended.
• src/help-content.ts — canonical-shape headers updated.
• tests/v0.15.2-execute-skill-name-kwarg.test.ts (NEW).
• tests/dogfood-t7.test.ts — version assertion.
• package.json — version 0.15.1 → 0.15.2.
• CHANGELOG.md — this entry.