fix(capabilities): require explicit intent for named groups

[seekskyworld]

Problem

Closes #303. Bare subagent/workflow references in identifiers, discussion, or comparisons were treated as authorization under explicit discovery, causing optional tool groups to load unexpectedly.

Value

Prevents accidental capability activation from pasted prompts and ordinary development vocabulary while preserving explicit delegation/workflow requests.

Approach

Require imperative English request forms for named capabilities, retain existing Chinese request forms, and add regressions for branch/file references and comparisons. Negated and conditional clauses continue to fail closed.

Validation

• node --test --experimental-strip-types tests/extensions/shared/capability-intent.test.ts (5 passed)
• git diff --check (passed)

Impact

• User-visible behavior: fewer false-positive capability highlights/loads.
• Model-visible tools: explicit requests unchanged; bare references no longer load groups.
• Runtime/lifecycle: no changes beyond intent classification.
• Persisted config/data: none.
• Compatibility/risk: prompts that relied on bare capability names must use an explicit request.