Promotes the previously session-local search-first write rule into the
canonical plugin and applies items 2-7 from echo-skill-improvements memory:
1. Loading Step 4 and a new mandatory pre-write search section now require
POST /search/simple/?query=<slug> across all four project lifecycle
subfolders before creating any slug-addressed note.
2. Daily-note Agent Log uses a resilient PATCH procedure that auto-creates
the daily note from the template if missing and adds the heading if
absent before patching.
3. New Style Rule: `created:` is the earliest known date, not "today";
preserve it on merges.
4. New Project Lifecycle section: incubating / active / on-hold / archived,
with the rule that folder and frontmatter.status must agree.
5. Session filename pinned to YYYY-MM-DD-HHMM-<slug>.md (lex-sortable);
existing files left as-is.
6. Loading Step 3: read only the ~5 most recent sessions by reverse lex
sort instead of the full list.
7. `source_notes` defined as a backward link to inputs; forward links
belong in `## Related` in the body.
Repo layout: promotes the previously zipped-only plugin to a tracked
source tree at echo-memory.plugin.src/. The .plugin zip is rebuilt
from source on each version bump.
Bumps plugin.json to 0.3.0.
jason