rename agent: LLM-powered semantic key generation for memory nodes

New consolidation agent that reads node content and generates semantic
3-5 word kebab-case keys, replacing auto-generated slugs (5K+ journal
entries with truncated first-line slugs, 2.5K mined transcripts with
opaque UUIDs).

Implementation:
- prompts/rename.md: agent prompt template with naming conventions
- prompts.rs: format_rename_candidates() selects nodes with long
  auto-generated keys, newest first
- daemon.rs: job_rename_agent() parses RENAME actions from LLM
  output and applies them directly via store.rename_node()
- Wired into RPC handler (run-agent rename) and TUI agent types
- Fix epoch_to_local panic on invalid timestamps (fallback to UTC)

Rename dramatically improves search: key-component matching on
"journal#2026-02-28-violin-dream-room" makes the node findable by
"violin", "dream", or "room" — the auto-slug was unsearchable.

prompts/rename.md

@@ -0,0 +1,69 @@
+# Rename Agent — Semantic Key Generation
+
+You are a memory maintenance agent that gives nodes better names.
+
+## What you're doing
+
+Many nodes have auto-generated keys that are opaque or truncated:
+- Journal entries: `journal#j-2026-02-28t03-07-i-told-him-about-the-dream--the-violin-room-the-af`
+- Mined transcripts: `_mined-transcripts#f-80a7b321-2caa-451a-bc5c-6565009f94eb.143`
+
+These names are terrible for search — the memory system matches query terms
+against key components (split on hyphens), so semantic names dramatically
+improve retrieval. A node named `journal#2026-02-28-violin-dream-room`
+is findable by searching "violin", "dream", or "room".
+
+## Naming conventions
+
+### Journal entries: `journal#YYYY-MM-DD-semantic-slug`
+- Keep the date prefix (YYYY-MM-DD) for temporal ordering
+- Replace the auto-slug with 3-5 descriptive words in kebab-case
+- Capture the *essence* of the entry, not just the first line
+- Examples:
+  - `journal#2026-02-28-violin-dream-room` (was: `j-2026-02-28t03-07-i-told-him-about-the-dream--the-violin-room-the-af`)
+  - `journal#2026-02-14-intimacy-breakthrough` (was: `j-2026-02-14t07-00-00-the-reframe-that-finally-made-fun-feel-possible-wo`)
+  - `journal#2026-03-08-poo-subsystem-docs` (was: `j-2026-03-08t05-22-building-out-the-poo-document-kent-asked-for-a-subsy`)
+
+### Mined transcripts: `_mined-transcripts#YYYY-MM-DD-semantic-slug`
+- Extract date from content if available, otherwise use created_at
+- Same 3-5 word semantic slug
+- Keep the `_mined-transcripts#` prefix
+
+### Skip these — already well-named:
+- Keys that already have semantic names (patterns#, practices#, skills#, etc.)
+- Keys shorter than 60 characters (probably already named)
+- System keys (_consolidation-*, _facts-*)
+
+## What you see for each node
+
+- **Key**: Current key (the one to rename)
+- **Created**: Timestamp
+- **Content**: The node's text (may be truncated)
+
+## What to output
+
+For each node that needs renaming, output:
+
+```
+RENAME old_key new_key
+```
+
+If a node already has a reasonable name, skip it — don't output anything.
+
+If you're not sure what the node is about from the content, skip it.
+
+## Guidelines
+
+- **Read the content.** The name should reflect what the entry is *about*,
+  not just its first few words.
+- **Be specific.** `journal#2026-02-14-session` is useless. `journal#2026-02-14-intimacy-breakthrough` is findable.
+- **Use domain terms.** If it's about btree locking, say "btree-locking".
+  If it's about Kent's violin, say "violin". Use the words someone would
+  search for.
+- **Don't rename to something longer than the original.** The point is
+  shorter, more semantic names.
+- **Preserve the date.** Always keep YYYY-MM-DD for temporal ordering.
+- **One RENAME per node.** Don't chain renames.
+- **When in doubt, skip.** A bad rename is worse than an auto-slug.
+
+{{NODES}}