docs(claude): refresh project tree, IDs line, and roadmap (audit F2/F3/F4)

- F2: add relicario-server crate to the project-structure tree
- F3: replace stale "Next: WASM + Chrome MV3 (Plan 2)" roadmap line with
  the v0.5.0/Phase-3/1C-γ/LastPass picture
- F4: ItemIds and FieldIds are 16-char hex (64 bits) per audit M8;
  AttachmentIds are first 32 hex of SHA-256 (128 bits) per audit I2/B4

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CLAUDE.md

@@ -48,9 +48,11 @@ crates/
 │   ├── src/helpers.rs      # vault_dir, git_command, iso8601
 │   ├── src/session.rs      # UnlockedVault (master key in Zeroizing)
 │   └── tests/              # basic_flows, edit_and_history, attachments, settings, vault_detection
-└── relicario-wasm/            # WASM bindings for the extension
-    ├── src/lib.rs          # #[wasm_bindgen] surface
-    └── src/session.rs      # opaque SessionHandle → Zeroizing<[u8;32]>
+├── relicario-wasm/            # WASM bindings for the extension
+│   ├── src/lib.rs          # #[wasm_bindgen] surface
+│   └── src/session.rs      # opaque SessionHandle → Zeroizing<[u8;32]>
+└── relicario-server/          # `relicario-server` binary (pre-receive Git hook)
+    └── src/main.rs         # verify-commit + generate-hook subcommands
 ```
 
 ## Key design decisions
@@ -76,7 +78,7 @@ passphrase (UTF-8 bytes) || image_secret (32 bytes from reference JPEG)
 
 - Tests use fast Argon2id params (m=256, t=1, p=1) so they don't take forever.
 - Test JPEGs are generated synthetically via `make_test_jpeg()` — no binary test fixtures.
-- Item IDs are random 8-char hex strings.
+- Item IDs and Field IDs are random 16-char hex strings (64 bits of OsRng entropy). AttachmentIds are content-addressed: first 32 hex chars of SHA-256 over the plaintext (128 bits).
 - Git history is preserved as an audit log — no squashing.
 - The CLI shells out to `git` for sync — no libgit2/gitoxide dependency.
 
@@ -90,4 +92,4 @@ Full threat model, entropy analysis, and architecture: `docs/superpowers/specs/2
 
 ## Roadmap
 
-Next: WASM build + Chrome MV3 browser extension (Plan 2). Then mobile (Rust core compiles to ARM).
+Next: v0.5.0 polish + harden (in progress). After that, Phases 3/4 of the fullscreen UX redesign (vault-tab shell + command palette), Plan 1C-γ (attachments + Document + trash/history/device UI), and the LastPass importer. Mobile (Rust core compiles to ARM) and recovery QR remain on the roadmap.