docs: repoint every reference the docs/ reorg left dangling

`docs/` was reorganised into topic subdirectories and the references to it
were not moved with it. Thirteen distinct paths and three relative links no
longer resolved, spread across nix, css, html, js, markdown and
.prettierignore — a stale pointer is not a markdown problem, it is wherever
someone wrote a path down.

Each mapping resolved to exactly one target. `docs/matrix.md` was the sole
ambiguous basename: .prettierignore lists `docs/tools/matrix.md` separately
and that entry still resolves, so the stale one is the integrations doc.

The three relative links were each one `../` too deep — from `<crate>/src/`
two levels reach the repo root. `hive-agent/src/login.rs` already had the
correct form, in the same crate, at the same depth.

.prettierignore is repointed rather than dropped, though nothing in the tree
runs prettier: no treefmt entry, no CI job, no package script. Whether that
config should exist at all is a separate question from whether it names
files that do.

docs/process/conventions.md

@@ -195,7 +195,7 @@ Per-variant fields:
   — `agent` is the affected agent (target of the spawn / config
   commit), not the asker. `description` is the manager's free-text
   blurb shown on the dashboard card. `commit_ref` is the
-  kind-specific payload (see `docs/approvals.md::Approval kinds
+  kind-specific payload (see `docs/agent-lifecycle/approvals.md::Approval kinds
   (wire shapes)`).
 - `Reminder { id, owner, message, due_at, age_seconds }` —
   `due_at` is the absolute time the scheduler is targeting (RFC
@@ -424,7 +424,7 @@ start runs across the `StopForUpdate → Swap → RebuildBookkeeping`
 brace and the tail `Reconcile` node. `flake.nix` itself is no longer
 regenerated host-side on rebuild — it's tracked in the agent's
 proposed/applied repos and rides along on every fetch (see
-`docs/approvals.md::Two repos per agent`).
+`docs/agent-lifecycle/approvals.md::Two repos per agent`).
 
 Anything that changes per-container state on the host should be
 re-applied here so a manual `↻ R3BU1LD` from the dashboard is
@@ -528,7 +528,7 @@ the state dir at provisioning time:
 
 (The matrix profile avatar is **not** a oneshot — `hive-matrix-daemon`
 sets it over its live authenticated Client; see
-`docs/persistence.md::matrix avatar`.)
+`docs/agent-lifecycle/persistence.md::matrix avatar`.)
 
 Shape contract — every one of these:
 
@@ -549,7 +549,7 @@ Shape contract — every one of these:
 5. **Re-runnable**: a second invocation produces the same final
    state (idempotent uploads, idempotent config rewrites). Used
    by the `.path` watchers that re-fire on token appearance (see
-   `docs/persistence.md::Matrix per-agent daemon`).
+   `docs/agent-lifecycle/persistence.md::Matrix per-agent daemon`).
 
 The artefact lives under the agent user's home where applicable
 (`~/.config/tea/config.yml`) and is chown'd to that user, but the