fix: gemma4 loader, fleet count, pap:// routing safety, address bar & chrome polish

[toadkicker]

Summary

Seven commits resolving the repeat issues from this session:

• Gemma 4 model loading — remap_gemma4_metadata() rewrites gemma4.* GGUF keys to gemma3.* before passing to quantized_gemma3::from_gguf(), which only probes the gemma3 prefix family
• Fleet total count — list_local_agents now includes DB-only catalog agents (tagged live=false) so the fleet badge shows ~350 instead of 4; active_count fixed to count only compiled agents
• pap:// routing safety — AgentInfo.live field gates catalog map inclusion; DB-only agents can no longer silently resolve pap://agent-name URIs to a handler-less DID (which would fall back to On-Device AI)
• pap:// autocomplete — typing pap:// in the address bar surfaces live agent names from CatalogState with arrow-key navigation, Enter to confirm, Escape to dismiss
• DB migration — additive ALTER TABLE agents ADD COLUMN for version and schema_version; fixes 300+ catalog agents failing to seed on existing databases
• Browser-style chrome — topbar redesigned with 3 zones: 64px brand (aligns with sidebar), full-width pill address bar (InlinePrompt promoted from canvas), single status dot; removes hamburger, DID display, READY badge, and settings gear from the header
• Logo clipping fix — brand zone is now icon-only (text hidden via display:none) to prevent clipping in the 64px constraint

Test plan

• Settings → Models → select Gemma 4 E2B → confirm no "gemma3.attention.head_count" error
• Fleet page → total badge shows 300+ agents
• Address bar: type pap://wiki → dropdown shows wikipedia-knowledge, wikipedia-summary, etc.
• Arrow keys navigate suggestions; Enter submits; Escape dismisses
• pap://duckduckgo-search → submits and resolves (not silently routed to On-Device AI)
• On a fresh DB (delete %APPDATA%\papillon\papillon.db): catalog agents seed without "no column named version" errors
• Topbar: butterfly logo centered in 64px, no clipping; address bar fills center; status dot only on right
• Sidebar settings gear still navigates to /settings; canvas dropdown opens from logo click

🤖 Generated with Claude Code

[github-actions]

Benchmark Regression Report

PAP Protocol Benchmark Regression Check
========================================
Baseline: .bench-baseline/baseline.json
Threshold: 30%

  ed25519_keypair_generation                22.1 µs  (baseline: 22.1 µs, +0.0%)  [ok]
  did_key_derivation                         1.6 µs  (baseline: 1.6 µs, +0.1%)  [ok]
  mandate_create_sign                       26.6 µs  (baseline: 26.6 µs, +0.0%)  [ok]
  mandate_chain_verify_depth3              132.9 µs  (baseline: 132.5 µs, +0.3%)  [ok]
  sd_jwt_issue_5claims                      31.2 µs  (baseline: 31.1 µs, +0.3%)  [ok]
  sd_jwt_verify_disclose_3of5               45.8 µs  (baseline: 46.3 µs, -0.9%)  [ok]
  session_open_full_lifecycle              123.4 µs  (baseline: 126.4 µs, -2.3%)  [ok]
  receipt_create_cosign                     53.3 µs  (baseline: 53.3 µs, +0.0%)  [ok]
  federation_announce_local                 60.0 µs  (baseline: 60.7 µs, -1.1%)  [ok]

All benchmarks within 30% of baseline.

_{Threshold: 10% regression vs baseline from main}