feat: preview channel agent activity in profiles

[kalvinnchau]

Change

• Add an Info-tab activity card with up to three recent assistant excerpts and tool titles/statuses, plus exact identity/channel View activity navigation.
• Reuse session-owned records and plugin capture; no new store, subscription owner, timer or cross-channel view.
• Parse scoped batch children directly, exclude prompts/thoughts/raw results, and split unkeyed messages at tool boundaries. Render bounded plain text; retained excerpts are not complete history.

Verification

At f8bfd36 on 82bb3a6 (includes #196 channel admission and #167 identity naming):

• Full Vitest: 2,852 passed with one worker; typecheck and mandatory pre-push hooks passed. Standard build and hosted DCO last verified at prior head 0c393a6; current hosted checks are separate.
• Chromium/WebKit: 14/14 activity/profile checks passed together, including incoming identity-name assertions. No timeout or retry changes.
• Four independent reviews reported no actionable findings at prior head 0c393a6, including signed nested-payload security and rendered segmentation checks. Latest rebase review requested separately; no approval carried forward automatically.
• Existing browser journey extended for real broker/profile navigation, content updates, remounts and screenshots; no browser cases added. Edge matrices remain in unit/mounted tests, with fail-before/pass-after allocation and segmentation regressions.

Live-owner/native, restart and sustained-load acceptance remain unverified; legacy raw-view formatting is unchanged. Hosted CI is a separate gate.

Originating channel: b9cb2c4d-d45c-4349-87b5-70f6b51390ac

buzz://message?channel=b9cb2c4d-d45c-4349-87b5-70f6b51390ac&id=991d99a2a7eca2e0e76a9e4262a566241383eda3f90e5bfa23bc43a8ff8279af

[wesbillman]

Carl, an automated reviewer, commenting via Wes’s GitHub account.

Review clear: no blocking findings. One non-blocking Unicode-clipping nit is inline. This is a comment review, not approval.

Reviewed f8bfd36d311a075a56f62d46e09dc538cb669c3d against 82bb3a631b96b92cd73940f16bcfb05fdaa7607e: signed identity and nested-batch channel scope, prompt/thought/raw-result exclusion, message/tool segmentation, bounded retained excerpts, exact identity/channel navigation, profile/thread context, store swaps, plugin ownership and access reset. Raw inspection/backfill and cross-channel views remain outside this preview’s contract.

Source-only on Blox: no checkout, installs, builds or tests executed. Existing exact-head CI #994 passed JavaScript, Rust/tool integration, browser measurements and all four Chromium/WebKit shards, superseding the earlier incomplete snapshot. Windows native validation was skipped. Live-owner/native, restart and sustained-load acceptance remain unverified; this is not release certification.