GeezerVison

<img width="1506" height="734" alt="Project page"
src="https://github.com/user-attachments/assets/bfcfba12-f229-4dfe-87a2-304bc0551ae1"
/>

Lists the project's unarchived chats below the composer, loaded from
`GET /api/v2/chats?project_id=` with infinite scroll. Each row shows the
status, title, PR state, owner, and AI Gateway cost (when enabled), with
the chat actions menu when the agents layout provides it. Row links keep
the sidebar's filter query string.

Adds the `projectChats` query factory, whose caches the previous PR
keeps in sync.

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Stack (merge top to bottom). #30377 through #29583 are f0ssel's split of
the original #29583, and this stack sits on #29583:
- #30377 data layer and project dialog (f0ssel)
- #30378 new-chat form locked to a project (f0ssel)
- #30379 project page route (f0ssel)
- #29583 sidebar folders (f0ssel), the base of this stack
- #30291 composer frame
- #30292 project chat list caches
- #30293 project page header
- #30294 project chats list 👈
- #30367 instructions storage and prompt injection
- #30368 instructions API
- #30369 instructions editor dialog
- #30370 instructions Details panel

---------

Co-authored-by: Garrett Delfosse <[email protected]>
Co-authored-by: Claude Opus 5.5 (1M context) <[email protected]>

…ion (#30367)

Adds storage for project-level instructions in Coder Agents chat
projects and injects them into every chat in the project. This is the
first of four stacked PRs that replace #30349.

A new `chat_project_instructions` table (migration 000613) holds at most
one row per project, scoped to the project's organization. It records
`updated_by` and cascades on project delete. The dbauthz wrappers
authorize against the parent project: read access to get the
instructions, update access to upsert or delete them. No new RBAC
resource is added; project RBAC comes in a later PR.

chatd loads the instructions on every turn, so edits reach existing
chats on their next turn. They are added to the system prompt as a
`<project-instructions>` block after the memory guidance and before
personal instructions, so a user's personal instructions still win a
conflict. Subagent chats carry no `project_id`, so they use their root
chat's project. A load error other than no rows is logged, and the turn
continues without instructions.

**What to scrutinize:** the prompt ordering in `buildSystemPrompt`, and
the choice to inject per turn rather than snapshot at chat creation.
Per-turn injection costs one prompt-cache miss after each edit; the org
instructions in #30272 use a creation-time snapshot instead.

**Generated** (`make gen` from the migration and
`queries/chatprojectinstructions.sql`): `dump.sql`, `models.go`,
`querier.go`, `queries.sql.go`, `dbmetrics/querymetrics.go`,
`dbmock/dbmock.go`, and the `*_constraint.go` files.

`coderd/x/chatd/ARCHITECTURE.md` gets two TODOs for the PR author to
replace with the real description, per AGENTS.md.

**Validation:** `make gen` leaves no diff. `go test
./coderd/database/dbauthz -run TestMethodTestSuite/TestChats`, `go test
./coderd/x/chatd -run 'SystemPrompt|ProjectInstructions|Memory'`, and
`go test ./coderd/database/migrations/...` pass.

---

Stack (merge top to bottom). #30377 through #29583 are f0ssel's split of
the original #29583, and this stack sits on #29583:
- #30377 data layer and project dialog (f0ssel)
- #30378 new-chat form locked to a project (f0ssel)
- #30379 project page route (f0ssel)
- #29583 sidebar folders (f0ssel), the base of this stack
- #30291 composer frame
- #30292 project chat list caches
- #30293 project page header
- #30294 project chats list
- #30367 instructions storage and prompt injection 👈
- #30368 instructions API
- #30369 instructions editor dialog
- #30370 instructions Details panel

---------

Co-authored-by: Garrett Delfosse <[email protected]>
Co-authored-by: Claude Opus 5.5 (1M context) <[email protected]>