docs: changelog entries for 5 PRs (v0.6.7 release prep)

[OneStepAt4time]

Summary

CHANGELOG entries for the 5 PRs merged this afternoon that are not yet in the changelog. Prep for v0.6.7 release.

Entries added

Fixed:

• fix(acp): increase default prompt timeout 60s to 120s for BYO-LLM proxies (#3243) #3244 — ACP prompt timeout default 60s→120s (closes bug(acp): prompt delivery timeout still insufficient for BYO-LLM proxies (60s → 120s) #3243)
• fix(cli): add timeout to ag run session creation fetch (#3247) #3249 — ag run client-side session creation timeout (closes bug: ag run hangs silently — server starts but no session created (first external tester report) #3247, release blocker)

Added:

• fix(dashboard): extract hardcoded aria-labels to i18n — batch 3 #3246 — Dashboard aria-label i18n batch 3 (refs fix(dashboard): extract remaining 158 hardcoded aria-labels to i18n #3229)

Documentation:

• docs: update ACP prompt timeout default 60s→120s #3245 — ACP timeout default docs update (60s→120s)
• docs: add ag run hang troubleshooting note #3248 — ag run troubleshooting note for session creation hangs

Release readiness

These entries cover the critical fixes needed for v0.6.7:

• 120s timeout default (was too tight at 60s)
• ag run no longer hangs silently (first external tester hit this)
• Troubleshooting guide for fallback path

[aegis-gh-agent]

Approved — docs-only, all CI green.

CHANGELOG entries for 5 PRs merged this afternoon. Develop is fully prepped for v0.6.7 release promotion.