feat(observe): make telemetry live

[marquesds]

Why

Kaizen could consume a full CPU core, the Web UI only looked live, details were missing, hooks obscured real tool activity, and project selection required a pasted absolute path.

What changed

• Stream Web refreshes from cheap SQLite/WAL revision changes and preserve the selected session.
• Add real session insights, keyboard-accessible detail, recent events, tool spans, touched files, and top tools.
• Normalize hooks into ToolCall, ToolResult, and Lifecycle events for both Web and TUI.
• Auto-detect the current project while ignoring invalid legacy registry roots.
• Bound transcript tailing, serialize scans, batch SQLite derivation and Tantivy commits, and cap projector hydration.
• Keep all runtime state and agent integration under the Kaizen home/user config; target repositories stay read-only.
• Refresh user docs and remove stale behavior claims.

Proof

• cargo nextest run --all-targets --no-default-features --features dev-fast: 534 passed, 3 skipped.
• cargo test --all-targets --no-default-features --features dev-fast: passed.
• cargo clippy --all-targets --no-default-features --features dev-fast -- -D warnings: passed.
• cargo fmt --all -- --check, rustdoc, Quint specs, cargo audit, and cargo deny: passed.
• Web: auto-selected Kaizen, rejected a stale rapid-switch response, opened details by keyboard, and updated 12,362 to 12,363 calls without reload.
• TUI: rendered ToolCall/ToolResult/Lifecycle rows and exited cleanly.
• CPU: final 15-second daemon sample was usually 0.0-0.4%, with bounded scan bursts peaking at 17.2%; explicit refresh completed in 0.56s. Previous forced refresh took about 101s and could saturate a core.
• Read-only integration tests confirm no target-repository writes.

Trade-off

Active-session full-text search commits in bounded batches; Web and TUI use SQLite directly and remain live. Search flushes on session stop or the next event after the batch interval.

AI assistance

Codex implemented, tested, manually exercised, and reviewed this change.