Release 0.15.0: Amplitude Analytics + Session Replay (with #21 Part C identity lifecycle)

Wave 5 / Track A. Roadmap item #13. Folds in #21 Part C user-identity-
lifecycle work inline rather than as a follow-up release (operator
ask: "implement Amplitude best practices from the very get-go").

Wraps @amplitude/unified with:
  - consent-gated lazy init (v0.13.0 cookie banner; SDK never loads
    without explicit analytics opt-in)
  - amplitude.initAll(KEY, { analytics: { autocapture: true },
    sessionReplay: { sampleRate: 1 } }) — vendor-recommended shape
  - identify({ user_id, properties? }) with set vs setOnce semantics
  - setUserProperties(properties) for mid-session state changes
  - anonymize() clears both user_id binding AND property cache

Wired into App.jsx (identify on me.user with role / permission_state /
passcode_set / device_trusted as set; first_sign_in_at / account_created_at
as setOnce; Page Viewed on route change; Sign-out fires User Signed
Out + anonymize), Login.jsx (User Signed In + Beta Access Requested),
and the per-feature surfaces (ProposeModal, PRModal, RFCView,
RFCDiscussionPanel, PRView, Admin).

Binding: VITE_AMPLITUDE_API_KEY via `flotilla overlay set`
(bundle-embedded public key like VITE_TURNSTILE_SITE_KEY — not
secret). Mid-Session-L correction: original dispatch brief specified
secret-set; vendor guidance + bundle visibility settled it as overlay.

PII discipline: no email, no display_name, no gitea_login, no free-text
fields ever sent. Properties are opaque ids + enums + timestamps +
booleans only.

Subagent ξ shipped the wrapper structure + nine-event taxonomy on
feature/v0.15.0-amplitude (0fd8c52 + 6cfbf69 post-correction).
Driver-side integration extended the wrapper with setUserProperties
+ identify properties for the #21 Part C identity-lifecycle work.
Frontend build verified green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/RFCDiscussionPanel.jsx

@@ -18,6 +18,7 @@ import {
   postDiscussionMessage,
   resolveDiscussionThread,
 } from '../api'
+import { EVENTS, track } from '../lib/analytics'
 
 export default function RFCDiscussionPanel({ slug, viewer }) {
   const [threads, setThreads] = useState([])
@@ -100,6 +101,10 @@ export default function RFCDiscussionPanel({ slug, viewer }) {
         void message_id
       }
       setComposer('')
+      // v0.15.0 — analytics: fire on a successful discussion post.
+      // surface=discussion distinguishes this from PR review comments
+      // which fire from PRView with surface=pr. No body text.
+      track(EVENTS.COMMENT_POSTED, { rfc_slug: slug, surface: 'discussion' })
     } catch (err) {
       setError(err.message)
     } finally {