* fix(chat): context meter reflects compression via session.context_breakdown RPC
The chat context meter read GET /api/sessions/{id} input_tokens — a
cumulative lifetime counter that compression never resets, so the meter
only ever grew and sat red after the first compaction.
Mirror the desktop: read live occupancy from the session.context_breakdown
WS RPC (context_used = compressor last_prompt_tokens, falling back to an
estimate of the live system prompt + tools + compacted history). The
compressor zeroes last_prompt_tokens when it runs, so the meter now drops
right after auto-compaction or /compress, exactly like desktop/web.
REST getSessionDetail is kept solely to feed the detail sheet's cumulative
token accounting. RPC failures keep the last known values; the meter never
blanks. Fixes#756.
* feat(chat): compressed xN badge on the context widget
The context chip now shows how many times the current session has been
context-compressed, sourced from the session.usage WS RPC (compressions =
context_compressor.compression_count) — the same usage snapshot the desktop
status bar reads. The badge explains a meter drop after auto-compaction or
/compress: the widget no longer just shows the number, it shows the story.
- UsageSnapshotResponse model + parseUsageSnapshot (Number-safe like the
breakdown parser — WS parser decodes JSON numbers as Double)
- compressionCount added to ChatUiState, reset on session switch/create/branch
- session.usage fires alongside session.context_breakdown in the 5s poll;
failures keep the last known badge value (best-effort, never blank)
- 3 parser tests; full local suite 615 tests green
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Co-authored-by: M57 <hy4ri@users.noreply.github.com>
