feat: multi-session terminal frontend UI + tests (PR 3)

- Add TerminalSessionTabs component with status dots, rename, close, max-5 limit
- Add 7 component tests for tab rendering, selection, close, rename
- TerminalComponent: sessionId prop, forwardRef with fit() method
- TerminalPage: multi-session orchestration, tab switching, auto-create default
- Fullscreen mode: Alt+Shift+F toggle, auto-hide tabs, Esc exit
- Keyboard shortcuts: Alt+Shift+N/W/ArrowLeft/ArrowRight/R
- Add CSS for tabs, fullscreen, mobile responsive
- Update useTerminalSessions hook for session CRUD
- terminal_manager.py: lookup by internal session_id fallback

Quality gates: tsc --noEmit clean, vitest (7/7 new tests passed), pytest (182 passed)

.atl/.skill-registry.cache.json

@@ -0,0 +1,3 @@
+{
+  "fingerprint": "c324de9e9faf30231900c691aca5f3a07c7db099"
+}

.atl/skill-registry.md

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+# Skill Registry — headquarter
+
+<!-- Auto-generated by gentle-pi extensions/skill-registry.ts. Run /skill-registry:refresh to regenerate. -->
+
+Last updated: 2026-05-27
+
+## Sources scanned
+
+- .opencode/skills
+- /home/alex/.config/opencode/skills
+
+## Contract
+
+**Delegator use only.** This registry is an index, not a summary. Any agent that launches subagents reads it to select relevant skills, then passes exact `SKILL.md` paths for the subagent to read before work.
+
+`SKILL.md` remains the source of truth. Do not inject generated summaries or compact rules by default; pass paths so subagents load the full runtime contract and preserve author intent.
+
+## Skills
+
+| Skill | Trigger / description | Scope | Path |
+| --- | --- | --- | --- |
+| `auto-commit` | Use when you are making multiple edits or completing significant work in a git repository to automatically create commits | user | `/home/alex/.config/opencode/skills/auto-commit/SKILL.md` |
+| `openspec` | Use OpenSpec as the source of truth for planning, implementation, verification, and archive discipline. | user | `/home/alex/.config/opencode/skills/openspec/SKILL.md` |
+| `openspec-apply-change` | Implement tasks from an OpenSpec change. Use when the user wants to start implementing, continue implementation, or work through tasks. | project | `/home/alex/projects/headquarter/.opencode/skills/openspec-apply-change/SKILL.md` |
+| `openspec-archive-change` | Archive a completed change in the experimental workflow. Use when the user wants to finalize and archive a change after implementation is complete. | project | `/home/alex/projects/headquarter/.opencode/skills/openspec-archive-change/SKILL.md` |
+| `openspec-explore` | Enter explore mode - a thinking partner for exploring ideas, investigating problems, and clarifying requirements. Use when the user wants to think through something before or during a change. | project | `/home/alex/projects/headquarter/.opencode/skills/openspec-explore/SKILL.md` |
+| `openspec-propose` | Propose a new change with all artifacts generated in one step. Use when the user wants to quickly describe what they want to build and get a complete proposal with design, specs, and tasks ready for implementation. | project | `/home/alex/projects/headquarter/.opencode/skills/openspec-propose/SKILL.md` |
+
+## Loading protocol
+
+1. Match task context and target files against the `Trigger / description` column.
+2. Pass only the matching `Path` values to the subagent under `## Skills to load before work`.
+3. Instruct the subagent to read those exact `SKILL.md` files before reading, writing, reviewing, testing, or creating artifacts.
+4. If no matching skill exists, proceed without project skill injection and report `skill_resolution: none`.