fix: v2.6.1 — panes start in their folder again after an update (#69), Changes panel stacks every repo, clickable paths in chat

- #69: tmux applies a pane's `-c` only while its server's own cwd exists.
  The server was forked from the dashboard's cwd (the plugin cache dir),
  outlives updates, and the old cache dir is pruned — after that every new
  pane started in a deleted directory, where `claude` died at once ("run not
  found") and a shell printed getcwd errors. tmux calls now run from `/`,
  and the pane's sh wrapper cds into its folder itself, which also heals a
  tmux server that is already stuck.
- Changes panel: a workspace's extra folders are sections stacked under the
  workspace folder (VS Code Source Control style), with Close repository /
  Close other repositories on a header's right-click.
- Chat: URLs and absolute paths are links; Claude Code's `[Image: source:]`
  line folds into its turn; uploads under `<data dir>/drops/` are listed.
- Update check: a checkout holding commits a newer release lacks reports
  `diverged_from_release` instead of offering a fast-forward that can only fail.

docs/API.md

@@ -698,7 +698,7 @@ otherwise `400 ENOWORKTREE`, never a fall back to the main folder. With it,
 
 Every `/api/lanes/:id/git…` route also takes `?source=<id>`: the read or write
 then works in one of the workspace's extra folders (Context → Folder), each
-its own repo — the Changes panel's folder picker. The tree is resolved from the
+its own repo — a section of its own in the Changes panel. The tree is resolved from the
 `lane_sources` ROW (`sourceFolder` in `server/lib/lane-sources.js`): a `folder`
 row of THIS workspace that is still a directory — otherwise `404 ENOSOURCE`
 (another workspace's row and a context-file row included), never a fall back
@@ -1571,7 +1571,7 @@ curl http://localhost:4820/api/sessions/sess_abc123
 GET /api/sessions/:id/outline
 ```
 
-The session's plan, the files it changed and what it used, read off its successful tool calls (`PostToolUse` events) and its prompts (`UserPromptSubmit`) — the activity panel of a Workspace Chat pane shown alone. `progress` follows `TaskCreate`/`TaskUpdate` by task id (a `TodoWrite` replaces the list wholesale); `outputs` are the paths written or edited with `Write`/`Edit`/`MultiEdit`/`NotebookEdit`; `files` the paths it only `Read` (a file it later changed moves to `outputs`); `uploads` the files attached to its prompts through the composer (paths under the `agenthub-drops-<uid>` dir that `POST /api/run/drop-image|drop-file` made); `memory` the Claude Code memory files (`.claude/**/memory/`) it read or wrote, kept out of the other lists. The path lists are newest first. `skills` are `Skill` calls; `mcp` are MCP server names (`mcp__<server>__<tool>`, a `plugin_` prefix dropped). A file made by a Bash command is not an output here. 404 for an unknown session.
+The session's plan, the files it changed and what it used, read off its successful tool calls (`PostToolUse` events) and its prompts (`UserPromptSubmit`) — the activity panel of a Workspace Chat pane shown alone. `progress` follows `TaskCreate`/`TaskUpdate` by task id (a `TodoWrite` replaces the list wholesale); `outputs` are the paths written or edited with `Write`/`Edit`/`MultiEdit`/`NotebookEdit`; `files` the paths it only `Read` (a file it later changed moves to `outputs`); `uploads` the files attached to its prompts through the composer (paths under the `<data dir>/drops/` dir — `agenthub-drops-<uid>` in older transcripts — that `POST /api/run/drop-image|drop-file` made); `memory` the Claude Code memory files (`.claude/**/memory/`) it read or wrote, kept out of the other lists. The path lists are newest first. `skills` are `Skill` calls; `mcp` are MCP server names (`mcp__<server>__<tool>`, a `plugin_` prefix dropped). A file made by a Bash command is not an output here. 404 for an unknown session.
 
 ```bash
 curl http://localhost:4820/api/sessions/sess_abc123/outline
@@ -1582,7 +1582,7 @@ curl http://localhost:4820/api/sessions/sess_abc123/outline
   "progress": [{ "id": "1", "subject": "Build the report", "status": "completed" }],
   "outputs": ["/home/me/work/Progress report.xlsx"],
   "files": ["/home/me/work/data/kpi.csv"],
-  "uploads": ["/tmp/agenthub-drops-1000/3f9a0c1d2e4b5a6c-minutes.xlsx"],
+  "uploads": ["/home/me/.claude/agenthub/drops/3f9a0c1d2e4b5a6c-minutes.xlsx"],
   "memory": ["/home/me/.claude/projects/-home-me-work/memory/launch.md"],
   "skills": ["xlsx"],
   "mcp": ["vercel_vercel"]