feat: per-change-block hunk actions (#50), codex lanes without a pipeline, macOS LaunchAgent

- git (#50): stage-hunk/discard-hunk take an optional `block` — one run of
  consecutive +/- lines inside an @@ hunk. `onlyBlock` (server/lib/git-diff.js)
  cuts git's fresh hunk down to it, folding the other blocks into the side
  being checked; LaneDiffView hangs one review bar per block (unified + split)
  and its arrows walk blocks.
- git exclude: entries AgentHub writes for a lane go to the COMMON git dir with
  the lane's path prefix (server/lib/git-exclude.js, used by router-apply and
  lane-mcp) — a linked worktree's own info/exclude is never read by git, and a
  subdir lane has no .git. MCP sync no longer fails with ENOTDIR on a worktree
  lane or creates a stray .git in a non-repo lane.
- codex lanes carry no pipeline: codex-ingest mirrors only idle/running,
  codex-nudge is removed, agents install writes nothing for codex, the
  Workspace hides stage/pipeline/feature pickers/PipelineMap for them, and
  every server start clears leftover codex stage data and the old AGENTS.md
  stage block.
- Changes panel: a whole file opens for reading and enters the editor on a
  click on its text (caret at the clicked line), not automatically.
- macOS: LaunchAgent start-at-login (scripts/launchd-service.js, picked by
  scripts/service-manager.js).
- Adds the AgentHub introduction slides and their image-embedding script.

AGENTS.md

@@ -11,42 +11,11 @@
 - Update docs whenever workflow or architecture changes — follow `skills/update-project-docs/` automatically at the end of every change-set (README + VN/CN/KO mirrors, ARCHITECTURE, wiki + i18n + cache bump, server/client READMEs, docs/*).
 - Every applicable source file you create or update (`.js/.ts/.tsx/.cjs/.mjs/.py/.sh/.css`) must start with the authorship header: a truthful file overview plus the exact line `@author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>`. See `skills/file-headers/` and `.claude/rules/file-headers.md`; verify with `bash skills/file-headers/scripts/check-headers.sh`.
 
-## Declare your lane stage as you work
+## Lane stage
 
-This repository is watched by AgentHub, its own dashboard. A **lane** is keyed by
-working directory, and the pipeline map only moves forward when the agent doing
-the work declares its stage:
-
-```bash
-agenthub stage <stage> --tool codex --evidence "<what is actually done>"
-```
-
-- Call it at every real transition — starting to plan, starting to implement,
-  running tests, opening the PR — not once at the end.
-- Stage names, `default` template: `intake → plan → implement → tests → review
-  → gate → ship → done` (the 16-node `ship-feature` template accepts these as
-  aliases too; `agenthub stage` warns on stderr and names the valid nodes if a stage
-  matches none).
-- **`--tool codex` matters.** One directory can back both a `claude` lane and a
-  `codex` lane, and without a tool the command fails rather than guess (it names
-  both candidates). Inside a pane the dashboard started you need nothing — that
-  pane carries `AGENTHUB_LANE_ID`, which outranks everything but `--lane`.
-- If `agenthub stage` reports that no lane owns the directory, this checkout was
-  never adopted: skip the stage calls and carry on. Stage reporting is
-  reporting, never control flow — a failed `agenthub stage` never justifies skipping
-  a step of the actual work.
-
-The dashboard also *infers* your stage from your tool calls (it reads Codex's
-own rollout journals — see `docs/LANES.md#stage-detection`), and on a codex lane
-that inference does move the pipeline map forward on its own. It still never
-counts as **evidence**: a node it moved through stays amber and never renders
-green. Only your own declaration does that — which is why the call above is
-worth making even when the map already looks right.
-
-If you hold a stage for a while with no evidence recorded, the dashboard may
-type a one-line `[agenthub]` reminder straight into this pane asking you to run
-`agenthub stage ... --evidence "..."`. That is the dashboard, not the user — treat
-it as the same instruction as this section and just make the real call.
+AgentHub's `codex` lanes carry no pipeline: the dashboard shows no stage for
+them and never infers or advances one, so there is no `agenthub stage` call to
+make while you work here as Codex.
 
 ## Where to work
 - `server/` for API/routes/data processing.