refactor!: rebrand CCAM to AgentHub

Clean break, no compatibility alias. Renames the product name, the CLI
binary (`ccam` -> `agenthub`), the env var prefix (`CCAM_` ->
`AGENTHUB_`), the Prometheus metric namespace (`ccam_*` ->
`agenthub_*`), the tmux session prefix (`ccam-lane-<id>` ->
`agenthub-lane-<id>`), the per-repo runtime profile directory
(`.ccam/profile` -> `.agenthub/profile`), the lanes state root
(`~/.claude/ccam-lanes` -> `~/.claude/agenthub-lanes`), the bundled
plugins (`plugins/ccam*` -> `plugins/agenthub*`) and their slash
commands (`/ccam-doctor` -> `/agenthub-doctor`, `/ccam:*` ->
`/agenthub:*`).

Because there is no alias, an existing install has to be updated by
hand: rename its `.ccam/profile` directory and any `CCAM_*` variables,
and reinstall the plugin under its new name.

Two other name families are deliberately left alone here, since they are
not just strings: the `Claude-Code-Monitor` repository/marketplace name,
and the `agent-dashboard` npm package plus its `~/.claude/agent-dashboard`
runtime directory, which holds the live database and needs a migration
rather than a rename.

Verified: server 1406/1406, client 459/459, `grep -i ccam` clean across
tracked files, `openapi.yaml` regenerated (95 paths, unchanged count).

server/data/profile-templates/postgres-compose/profile.env.example

@@ -1,5 +1,5 @@
 # postgres-compose profile template — data-isolation additions (A2).
-# Copy the declarations you need into your repo's own .ccam/profile/profile.env
+# Copy the declarations you need into your repo's own .agenthub/profile/profile.env
 # alongside db-create.sh / db-drop.sh from this template's hooks/ directory.
 
 DB_PREFIX="myapp_l"          # lane in slot 3 -> myapp_l3 ; empty = no per-lane DB
@@ -11,13 +11,13 @@ REDIS=1                      # 1 = allocate a logical Redis index = slot
 
 ENV_FILES="backend/.env"                          # file(s) to seed, relative to the lane
 ENV_SOURCE="backend/.env"                         # source path in the source repo
-ENV_REWRITE="DATABASE_URL REDIS_URL UPLOAD_DIR"   # keys CCAM overwrites per lane
+ENV_REWRITE="DATABASE_URL REDIS_URL UPLOAD_DIR"   # keys AgentHub overwrites per lane
 ENV_PRESERVE="JWT_SECRET"                         # keys kept from the lane's OWN file on --force
 UPLOAD_SUBDIR="backend/data/uploads"              # exported as UPLOAD_DIR
 
-# Read by db-create.sh / db-drop.sh, NOT by CCAM itself:
+# Read by db-create.sh / db-drop.sh, NOT by AgentHub itself:
 COMPOSE_FILE="docker-compose.yml"   # relative to the lane's working copy
 DB_SERVICE="postgres"               # the compose service name running Postgres
 
 # Machine-level credentials (PG_HOST/PORT/USER/PASS, REDIS_HOST/PORT) come
-# from ~/.ccam/secrets.env, never from here — see server/lib/secrets.js.
+# from ~/.agenthub/secrets.env, never from here — see server/lib/secrets.js.