docs(speech): reconcile proactive profile evidence

[luke-n-alpha]

What changed

• register UC15 across the V-model indexes
• distinguish contract/integration evidence from native Tauri evidence
• document the remaining packaging blocker in fix(packaging): stage-agent resolves workspace file dependencies outside projects/ #382
• state the personal DJ and exhibition-introduction acceptance boundary without overclaiming

Validation

• focused speech profile command tests: 8/8 passed
• markdown diff check: passed
• native Tauri coverage is already on main via test(speech): cover proactive profiles through Tauri #381

This PR documents the current packaging blocker and does not close #382.

[luke-n-alpha]

Focused verification passed. Merge is intentionally not forced: the remaining failing gates reproduce repository-wide findings already present on main (OSS-readiness: 6 findings; logging: 2 findings) and are outside this documentation-only diff.