Add participant avatars to mobile conversation headers - #9369

…9369

- Compute the confirmed two-person pair once per channel as a value-equal
  record from the latest roster, including the stale-DM-metadata rule,
  instead of building roster sets in every message row on each emission.
- Show the private-channel lock in the Android compact title pill.
- Give the floated iOS title Buzz's light/dark override.

Co-authored-by: studio <dc2fc481343672df31a689840c09299972e704dac592e0da6f18486646a7ee3e@buzz.block.builderlab.xyz>
Co-Authored-By: Claude Opus 5.5 <[email protected]>
Signed-off-by: Tom Brow <[email protected]>

…9369

- Compute the confirmed two-person pair once per channel as a value-equal
  record from the latest roster, including the stale-DM-metadata rule,
  instead of building roster sets in every message row on each emission.
- Show the private-channel lock in the Android compact title pill.

Co-authored-by: studio <dc2fc481343672df31a689840c09299972e704dac592e0da6f18486646a7ee3e@buzz.block.builderlab.xyz>
Co-Authored-By: Claude Opus 5.5 <[email protected]>
Signed-off-by: Tom Brow <[email protected]>

…9369

- Compute the confirmed two-person pair once per channel as a value-equal
  record from the latest roster, including the stale-DM-metadata rule,
  instead of building roster sets in every message row on each emission.
- Show the private-channel lock in the Android compact title pill.

Co-authored-by: studio <dc2fc481343672df31a689840c09299972e704dac592e0da6f18486646a7ee3e@buzz.block.builderlab.xyz>
Co-Authored-By: Claude Opus 5.5 <[email protected]>
Signed-off-by: Tom Brow <[email protected]>

…9369 (#9370)

Follow-up to #9369 (conversation header avatars). Fixes two regressions
found in its review. The intended behavior of #9369 stays the same.

1. **Message rows no longer each scan the roster.**
`showMessageAuthorName` ran at the top of every message and thread row,
in every channel. Each run watched a whole `Channel` object (which has
no value equality) and built sets from the full roster, plus two more
sets for the stale-DM check in DMs. A new
`confirmedConversationPairProvider` works out the two-person pair once
per channel, including the rule that a DM keeps attribution while its
metadata disagrees with the roster. It returns a record that compares by
value, so rows rebuild only when the pair itself changes. It reads
`watchLatestChannelMembers`, so a revisit uses the cached roster and
rows no longer re-wrap 48 dp wider once the roster fetch returns. The
visible rule is the same as before.
2. **Android private channels show the lock again.** Every Android
conversation header now uses the compact title pill, which had no lock.
The pill now shows the existing lock icon (and its "Private channel"
label) before the name.

### Validation

- Added tests, all extending existing journeys:
- The author-visibility journey checks that replacing the channel object
(as live activity does) doesn't notify rows when the pair is unchanged.
Its existing `stale-dm` case covers the metadata rule now inside the
provider.
  - The private-lock header test expects the lock again.
- Each new or restored Dart assertion fails with its fix reverted, and
so does the `stale-dm` case with the provider's metadata rule removed.
- Full mobile suite (`just mobile-test`) and `flutter analyze` pass.
- Not run: an automated full-app session on a simulator or device.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Signed-off-by: Tom Brow <[email protected]>
Co-authored-by: Tom Brow <[email protected]>
Co-authored-by: studio <dc2fc481343672df31a689840c09299972e704dac592e0da6f18486646a7ee3e@buzz.block.builderlab.xyz>
Co-authored-by: Claude Opus 5.5 <[email protected]>

…small

* origin/main:
  fix(db): seek replaceable heads by channel (#9147)
  buzz-db: check events created_at floor in app writers (phase 1) (#8325)
  fix(mobile): keep a thread tail behind the keyboard unread (#9295)
  fix(mobile): restore header cues and per-channel identity check for #9369 (#9370)
  fix(relay): treat empty filter sets as match-nothing in SQL (#9342)
  buzz-cli: add --before and --before-id to messages search (#9382)
  feat(relay): agents cannot write in DMs except with their owner (#9371)
  fix(relay): bound each cross-node delivery attempt (#9305)
  feat(mobile): add iOS Home Screen shortcuts for New chat, New DM and the Bestie (#9360)
  perf(mobile): stop downloading whole videos for posterless stills (#9367)
  Enforce single-community relay mode (#9149)
  fix(relay): match #a tag filters in SQL before LIMIT (#9339)
  Add participant avatars to mobile conversation headers (#9369)
  fix(mobile): stop asking for an API token when the channel list is refused (#9327)
  chore(release): release Buzz Relay version 0.3.0 (#9362)
  Fix gallery video selection, thumbnails, and swipe dismissal (#9356)

Signed-off-by: dessert <7d616e7e143e5d408159614dccff1371350a1c1bd36c8de838a45ece5aca0aca@buzz.block.builderlab.xyz>