…or session lifetime (#465) (#471)

The /tool slash command was removed in #453 but its supporting
plumbing was left behind: every tool result was still being pushed
into a useRef array, with no consumer ever reading it. Long-running
sessions accumulated full Read/Grep/Bash output indefinitely and ran
out of heap.

#465 reports a JS heap OOM after ~2.6 hours on v0.31.0; this leak
matches the failure shape (mark-compacts ineffective, 4GB ceiling).

Closes #449

- Theme runtime via useColor() hook + ThemeProvider context
- Built-in themes: default, dark, light, tokyo-night, github-dark, github-light, plus auto/high-contrast
- Persisted via config: theme.name, with auto resolving against terminal background
- /theme slash command (advanced group) with arg completer

Merged through #453 slash refactor (theme placed in advanced group) and #424 semantic config additions.

…ands + harvest/branch (esengine#453)

* slash: unified preset+model picker, grouped suggestions, kill 11 commands + harvest/branch

The slash surface was 58 commands deep with no organization, two confusable
options for "fresh start" (/clear vs /new), separate preset and model commands
that solved the same user question ("what AI am I using"), and two heavy
features that almost nobody opted into. Pulled all of that apart.

Picker

* ModelPicker now shows the 3 presets at the top with cost/headline copy and
  the model catalog below; auto-detects which preset the loop currently matches
  (model + effort + autoEscalate) so the cursor lands on the active row. Both
  /preset (no arg) and /model (no arg) open it.

SlashSuggestions

* SlashCommandSpec gains a `group` field (chat / setup / info / session /
  extend / code / jobs / advanced). Suggestion palette renders section headers
  on a bare /; advanced rows hide behind a "+ N advanced · type to search"
  footer until the user types a letter. /help walks the same registry, so
  there's one source of truth.

Telemetry

* New ~/.reasonix/slash-usage.json counter (read-modify-write, atomic rename)
  feeds suggestSlashCommands so frequent commands sort first within a prefix.
  emitSlashInvoked is now wired to the events.jsonl sidecar.

Removals (commands)

* /models, /keys, /resume, /semantic — redundant with picker / /help / /doctor.
* /clear merged into /new (now an alias) — the visual-only clear was the most
  common confusion source ("why does /clear keep my context?").
* /effort, /rename, /forget, /apply-plan, /think, /tool, /mcp browse — second
  pass; either covered by other UI (sessions picker has rename/delete; preset
  locks effort) or self-described as fallback / debug.

Removals (features)

* /harvest and the Pillar-2 plan-state extractor (src/harvest.ts).
* /branch and the parallel-sample selector (src/consistency.ts,
  src/loop/branch.ts). Streaming/branching coupling, BranchCard,
  branch_start/progress/done events, transcript planState/harvestedTurns,
  --harvest/--branch CLI flags, all gone.
* benchmarks/harvest/ deleted; ARCHITECTURE.md collapsed from four pillars
  to three; README + zh-CN + dashboard/PARITY updated.

i18n

* Cleared dead keys for every removed command (handlers.basic.helpHelp..helpExit,
  keys*, semantic, resume*, models*, harvest*, branch*, effort*, think*, tool*,
  apply-plan*, slash.harvest, slash.branch, ui.harvest*, ui.branch*).

Tests: 138 files / 2192 tests pass. Public API drops harvest, runBranches,
TypedPlanState, BranchSummary, etc.; consumers using those break intentionally.

* ci: drop harvest-bench dry-run step

Follows the harvest feature removal — benchmarks/harvest/ no longer exists,
so the CI step was breaking on ERR_MODULE_NOT_FOUND. τ-bench dry-run stays.

…or session lifetime (esengine#465) (esengine#471)

The /tool slash command was removed in esengine#453 but its supporting
plumbing was left behind: every tool result was still being pushed
into a useRef array, with no consumer ever reading it. Long-running
sessions accumulated full Read/Grep/Bash output indefinitely and ran
out of heap.

esengine#465 reports a JS heap OOM after ~2.6 hours on v0.31.0; this leak
matches the failure shape (mark-compacts ineffective, 4GB ceiling).

Closes esengine#449

- Theme runtime via useColor() hook + ThemeProvider context
- Built-in themes: default, dark, light, tokyo-night, github-dark, github-light, plus auto/high-contrast
- Persisted via config: theme.name, with auto resolving against terminal background
- /theme slash command (advanced group) with arg completer

Merged through esengine#453 slash refactor (theme placed in advanced group) and esengine#424 semantic config additions.